I actually asked the same question to my Dynamics professor a couple weeks ago. it's because Mu isn't a constant. Mu concentrates all the factors that go into two surfaces gripping each other all into one term. If Mu were to be expanded you would see that it depends on surface area in contact, material properties, external conditions, etc. In most cases where the friction equation is used, you can assume that Mu is correct within a certain tolerance. in the case of car tires though, there's a lot of factors that cause Mu to vary wildly and so in this instance the friction equation is used as an approximation at best. Love the vid
Asked my dynamics prof the same thing when I took it haha. The other factor is that the traction a tire produces does not actually increase linearly with the vertical loading. Essentially, the coef of friction decreases as the stress in the tire increases. This means that lowering the initial stress in the tire(larger contact area) will produce a higher tractive force under the same loading(the loading ceiling before mu decreases is raised). That is especially true in high downforce applications, but there is still significant load transfer from cornering.
@@tristanhanley8741 oh nice! Thanks! I’m majoring in aerospace and dynamics is kicking my ass so I’m glad to hear the same thing from someone else haha❤️
Yep same exact story for me when I was taking those courses 10 years ago. Me being a gearhead helped in some areas but that was one where I was at a definite disadvantage in terms of having to ignore or unlearn some preconceived notions and mental shortcuts for exam. My instructor brought up pretty much the same as yours as well as pointing out that for the sake of exams and theoretical calculations you're always assuming a perfect interface, but of course that isn't the case in reality even on a prepped race surface, and by going with wider tires you can think of it functionally as if you're casting a broader net to achieve that optimal surface to surface interaction.
@@tristanhanley8741 So would that make the equation a f''(x) of the frictional equation, similar to how acceleration is just the second derivation of position? or maybe its the 3rd derivation such as jerk is? Thats my initial guess.
Actual Tire Engineer here: the reason why you can get more than 1G grip and the reason to run wider tires on a race car has to do with shear strength! When the tread rubber goes into the peaks and valleys of the road surface, your extra grip comes because you have to physically shear off that portion of rubber to move the tire off that spot, the hot tread rubber has penetrated into the grooves & crevices in the road surface so it tears off rather than slides across. That’s why burnouts and donuts leave black marks, it’s rubber that was sheared off. So why wider? Because as you put heat into rubber, it is easier to shear, so a wider tire distributes the heat better but also has more individual peaks and valleys to shear pieces of rubber off. My quiz for you Jer: how does a tire keep the wheel off of the ground? Why doesn’t the wheel just squeeze the sidewall down until it is touching the road like pinching a balloon? You can compress the sidewalls by hand, so why don’t they just squeeze out of the way when the car is loaded on it?
This makes a lot of sense. I had a feeling it was to do with shear strength and immediately though of increased area therefore reduced stress, however I quickly debunked myself because Fz = P*A and obviously the pressure and weight on the tire are assumed constant therefore the area does not change amount, just shape. Could the fact that the contact patch become wider and less long with a wider tire also help with grip because more of the area is contacting fresh concrete, not rubber filled "dirty" concrete? The explanation on local heat leading to lower shear strength makes lots of sense!
As was explained: in addition to the frictional force, the tire is also pushing itself off these small peaks in the road. This is not a frictional contact but simply a "stuff pushing itself off other stuff" contact. Normal force is directly transferred between the tire and road in forward direction. A wider tire is the only option to increase the quantity of little mountains the tire can push itself off and therefore increases the overall amount of grip. The mu value for grip is just a good enough approximation for normal everyday (I.e. Not drag racing) use. Sorry for lacking some words. It's really hard to explain this stuff in a foreign language
on top of tire construction and so fourth a balloon is made to stretch a car tire is not a drag slick is closer to a balloon concept as it starts out as a wide tire and the higher the speed it grows taller reducing width to gain diameter it is also used as a gearing aid i could go on and on
on top of all of this sorry one last thing a wider tire makes up for a larger tire in diameter and its really the end of the story there its to keep the tire from having to be 40 inches tall to keep a contact patch on the ground the same as a shorter tire that is wider carry on
I love Jeremiah, he's got to be the BEST at explaining techy things all in layman's terms while being fun. Great presenter. I come back every week for all Donut's videos, but he's my favorite to watch.
@@IgnitionP Not really. I came for studying science but this guy just irritated me. Most geeks like me would not like these types of jokes as they are too obvious & cheap
Engineer here. The equation Friction = (coefficient of friction)*(Normal Force) doesn’t tell the whole story. As the normal force increases, the coefficient of friction actually goes down slightly. This explains why body roll causes the car to lose grip. More weight is put onto the outside tire, but the coefficient of friction of that tire is now lower than what it was before, which means that the total force that stops you from sliding decreases. The reason why you want wider tires is twofold. First, wider tires can absorb and dissipate more heat that narrow ones. So if you’re generating lots of heat from racing for example, narrow tires would get too hot and overheat, causing decreased traction. Secondly, if the same force is distributed over a larger area, the pressure the tire feels goes down. This makes the coefficient of friction go up, since each tiny section of tire is feeling less weight on it, because there are more sections to distribute that weight. TLDR; more weight, lower coefficient of friction. Distribute that weight over more surface area, coefficient of friction goes up. Higher coefficient, higher grip.
Yes and no. Normal force is a multiplier of mass. So a heavier vehicle will have more traction than a lighter vehicle on the same tires. It just takes more energy to make it accelerate and decelerate.
this is the first correct answer I've seen. good job side note, you shouldn't confuse body roll and weight transfer. while they're related, they aren't the same thing. second side note: a bigger tire isn't always faster. while it can give you more grip by allowing you to run a lower pressure for the same load carrying capacity, it also means more mass to accelerate out of the corner.
On the topic of wear bars, one thing I think is cool about the Continental ExtremeContact DWS tires (which are great by the way) is a built in wear indicator. There's a D (dry), W (wet), and S (snow) imprinted in the tread blocks that will wear out in reverse order. When the S is gone, it means they aren't ideal for snow anymore. Then the W wears out, meaning they no longer are good in the wet. Then the D, obviously meaning dry traction is no longer ideal. It's just a cool little system they have that simplifies reading what stage your tread wear is at. Slick bit of kit if you ask me.
That's not want the world needs. If he was just a science class teacher only a few would learn. Now we ALL get to learn and he influences young minds all over the world.
wider tires aren't making any single point stickier they're just allowing a larger distribution of the forces. lower force over a given point will result in less slip.
To put it in even simpler terms, for a larger tire you'll get a larger contact patch. And while the contact patch is horizontal, the shear force is what matters here. So, the actual ability to grip comes from not just the theoretical friction force, but also the ability for both surfaces to remain in place. If you have a smaller tire with the same forces, it's more likely that the tire or ground will start to break down. This can be seen most closely with the grooves made in roads by semi trucks, as they are heavily loaded and are able to quite literally push the asphalt away as opposed to simply pushing off of that asphalt.
On top of all that, many of these tires are also made to bond to the asphalt. More patch means more bonds, and more bonds means more resistance to sliding. This translates to a higher real world friction coefficient.
This is all too complicated for me. Someone please explain to me very simply, why does a road bicycle tyre (think tour de france tires, 2-4cm wide) have such good grip, even though it's so slim?
14:10 wider channels between lugs (particularly on more offroad focussed tyres like mud terrains) actually help the tyres to self clean when driving through mud and sand so that when the next part of the tyre becomes the contact patch it isn't full of slippery mud. All terrain tyres tend to get filled with sand or mud which does help on soft sand but is completely useless in mud as they don't self clean. The wider channels also help the lugs to deform around rocks when they are let down to give the tyre as large a contact patch as possible when driving over rocks and the like.
The reason why drag racers have wider tires is to introduce more points for the tire to enact force on the "peaks" of the road surface. In an introductory physics course most of your teachings and understanding is on a single point of contact, or particle. So the friction equation F_f = \mu * F_n, can be scaled according to however many particles, or instances of contact you have. That's also why drag racers use softer tires, and often deflate them, so than can introduce more instances of contact to the road/track surface. For example if you have a tire so small, where it only makes contact with only one peak in the road surface, even in a heavy vehicle, the force of friction will still be relatively small compared to it's weight. It's like have only one one person push a brick wall, but if more people push the wall, eventually the wall will topple. You also cant forget there are two different types of friction, static and kinetic. Static, for when an object is usually at rest and trying to move; and Kinetic, for when an object is usually moving, and is trying to stop. Coefficients of static friction are typically smaller coefficients than kinetic friction, meaning it's harder for the weight (which is "equal opposite" of normal force) to act on the tires regards to get gaining Grip. -UCF Aerospace Engineering undergrad Also, I love you guys!
In layman terms, more surface area to contact with... just as intuition would say. Maybe there is nothing that accounts for a definite area in an equation somewhere, it's essentially still the same thing, in a roundabout way. More points of contact literally translate to a bigger surface area. That's quite literally what an area is, a lot of discreet points next to each other. Deflating a tire just increases the contact are with the road as it sags more under the same load. I understand what you say but it seems the question is more philosophical than describing reality.
This is not exactly true, theoretically in the simple friction formula area does not matter. Even if a mack truck only contacted one peak, the available friction force would be the same. The answer to the question is the coefficient or friction is not constant with tires compounds. The coefficient itself is inversely proportional to surface pressure. That's why the simple physics formula you learn in your undergraduate generally fails when you consider tires. With the simple formula there is no reason that a truck takes any longer to stop it than a motorcycle. ( Mechanical engineer )
Anyone else miss the old B2B where James would get an interesting car and go into detail about it from front to back. Love the series that Jeremiah does though!
Actually, not trying to throw shade, but James is my least favorite presenter, because he is always trying too hard to be over-demonstrative. It seemed very natural in the early vids years ago, but now days it comes off as trying too hard. Where Jeremiah comes off much more naturally most of the time, but he also pushes into that "James Zone" from time to time. But a lot less than James actually does. Either way, I like all of them. It's just in varying levels.
The answer is Hector is going to be running 3 Honda Civics with SPOON engines. And on top of that, he just went into Harry's, and he ordered 3 T66 TURBOS, with NOS. And a MOTEC exhaust
@@WhatZitTooYaaa i think thats kinda the whole point of that line. Dismt want too include any real companies other then nos because nos is a brand and its well shown off in FF so they either sponsored or idk. The spoon engine is real but its not actrually called a spoon engine. I think its a very specific honda crate engine(not made by honda) and their like 30-40k and dont exactly make alott of power but their made too handle more power then any axle you can fit in those cara coupd handle😂
If we’re talking about Top-fuel dragster’s they use an extremely low tire pressure (I think 5-10psi)so they can use the affect of acceleration on the low pressure to change the circumference during acceleration and use this affects as a sort of gear box, when the car the launch’s the circumstance is the biggest it’s gets and along the run the circumference gets smaller to change the supposed gear ratio through the tires. Absolutely fascinating stuff. (I think top fuel dragsters officially only have 2 gears in they’re gears box)
Zacharia Weisman : You have the getting bigger vs smaller thing backwards. It starts off small then at speed it increases diameter due to centrifugal force. It does in effect change the final gearing.
Him throwing the vulcan hands up while saying "messaa loved the new star wars movies" in Jar Jars voice made me die a little inside lol. Our beloved childhood franchises are so lost.
Tire Test Engineer here. I will say this was a great and informative video, love these from Donut Media! Tread pattern design is not just for looks though, that does come into play some, but the shape of the tread pattern will be driven by tire noise too. A passenger car tire is designed to minimize road noise while a wet race tire is designed for maximum water evacuation. Having tested about every tire type, a wet race tire does the best job at evacuating water from the contact patch, but they are extremely noisy tires in both wet and dry surfaces, this is comparing slicks and wets with the same compounds and constructions. The average customer would not want a tire as loud most of the wet race tires. Keep up the great content!
@@Kottam_Yallawa if you aren't here to learn about tires, feel free to go look at pictures of cats and shut your brain off, since you obviously don't value it
Answer: wider tyres increase odds of getting the maximum friction the surface has to offer. Also lowers pressure per unit area which lowers overall wear.
I think your right! I am not a engineer but I did read the other comments and they look right when I looked what they said on google. Basically the reason why larger tires give more grip is because the world is not perfect and there is sometimes gaps between the tires and the ground, and making them larger gives you more chances to touch the ground. Though in a perfect world a small tire and a large tire would have the same amount of grip.
no that's not actually the case. it's because Mu in the friction equation is a variable not a constant and surface area plays a huge role in determining the value of Mu
Uh, depressuring your tires increases wear, the sidewall isnt meant to take excessive loads when under aired, you can risk bubbling or debeading because your tire isnt keeping its shape
@@pleasedontwatchthese9593 The most used Racing tires are a slick, meaning no tread. Just a giant contact patch. Formula 1 uses either slicks in dry conditions and a lightly treaded pattern in wet conditions. If it were a perfect world we would all be running slicks optimizing grip to a n almost 100% degree of contact.
@@ultimatum117052 He's not talking about the air pressure of the tire, to my understanding he is refering to the same pehomena that makes snowshoes work. Larger footprint = weight being distributed on a larger area. If you have a 5 square inch contact patch and your ''car'' weighs 100lbs, you apply 20 lbs per inch on the ground of pressure, if you now have 10 square inch contact patch but the same weight, you now apply 10 lbs per inch. so in that sense, the tires would last longer. If that makes any sense lol
I just got the continental DWS06 tires and it's rained twice since then I've purposefully tried to lose traction to compare to my old. I highly recommend them they are very grippy
A lot of people have already attempted to answer this, and I might just get lost among the other thousand comments, but I'm learning about this in a physics class this semester so I thought I might take a crack at it. The reason that F_f (force of friction) is not dependent on surface area is that when surface area is larger, the weight force (F_g) is spread out more across the surface area. Essentially, larger surface area means less weight per unit of area. However, the reason that drag racers use larger tires (I think) is that on a drag course with a treated surface that has whatever sticky substance on it, friction is not the only force acting between the tire and the road.The adhesion (ability to stick to other things) of the sticky substance is very high, and when there is more surface area on the tire, there is more surface area for the tire to adhere to the sticky stuff. However, I don't know too much about drag racing so I may be wrong about sticky stuff.
That's all makes sense, but that leads to the question why normal sports cars or race cars have so wide tires? Why are the Corvettes tires so much wider than a Honda civics tires?
I have a feeling it's about the tire wear. for example, if a 1in by 1in section of a tire can only take a certain amount of force then on a skinny wheel you will exceed the limit of the 1in by 1in section. but on a wide tire, the tire doesn't exceed the maximum amount that section can hold because there is physically more surface area for the tire to hold.
frictional coefficients are not constant between two materials. there often is a pressure dependency. for rubber a higher pressure means a lower coefficient of friction and less grip. adhesion is one of several friction mechanisms present in tires. drag tire tread compounds have friction coefficients much higher than 1.
@@bolt5564 I think that’s more to do with use cases. Wider tyres are a huge draw to fuel efficiency and even some power, so unless the benefit of extra grip sometimes isn’t worth what you’re losing
Wider tires are able to use softer compounds, therefore have a lower coefficient of friction. So a drag car has extremely soft and wide tires with a really high coefficient of friction. As the tires get narrower, the coefficient of friction goes up due to the compound getting harder. In regards to cornering, the wider the tire, the stiffer the side wall leading to less rolling in the tire.
When creating a good compound for acceleration, softer compounds are favoured however an issue with softening the compound is that it will no longer support the weight of the car. To alleviate this, widening the tire and potentially using different compounds in different areas, along with stiffening the sidewalls helps to increase the weight the tire can support as well as improving cornering performance as the tire also experiences less roll. This widening gives a larger contact patch with the surface also, again helping to even out irregularities in a surface, increasing stability and grip.
My (hopefully) educated guess for the last question regarding the absence of surface area in the formula of friction force goes like this. It does not influence the linear movement grip, but it highly improves cornering grip, the same way in which wider bodies improve cornering stability. A good way to visualize these scenarios is to take some exaggerated versions of the extremity-scenarios: imagine a car with bicycle wheels. When cornering, a narrow tire will bend towards the inside of the corner (relative to the rim), moving the contact patch towards the lateral side of the tire, and rendering the highly engineered middle of the wheel useless, since it loses contact. A wider tire will have a much harder time bending like that, since it is supported by forces further apart, thus maintaining the contact patch in the area the tire is designed to have it. Same reason why low profile (hope that's the correct terminology) tires will perform better when cornering on smooth surfaces: bending is limited. A seemingly counter example would be the high profile tires of Formula 1 cars, but they are smooth everywhere, anyway, so even if the contact patch moves to one side, the road will still see the same type of tire surface, and would behave the same (assuming same chemical composition on said surface). That's my two and a half cents, hope I'm not way off. If you got this far reading my long comment, might as well leave me a like to show that you agree ;) Great content my dudes, love your vibes and appreciate your powerless communication which makes you so much more relatable and enjoyable. Peace out. Edit: Uziel Lavine's answer seemed pretty persuasive as well, for the microscopic aspect of it. As a macroscopic view, I still think my point stands. I see people posting their backgrounds, I'm a physicist engineer. :)
This is true but he does also ask in relation to ‘drag racers’. They generally don’t require cornering at high speeds as they are straight line cars. From what I remember hearing from my mechanic mates, a wider tire profile for drag cars are generally to benefit ‘off the line’ response. This is also why the back tires are much wider than the front tires. To accelerate, the engine must apply force to the driving wheels (which with most drag racers, is RWD). When you accelerate, weight transfers from the front of your vehicle to the rear. My mate likened it to a sprinter launching from running blocks. The sprinter will ‘launch’ faster because the running block is providing a resistant, otherwise theoretically the sprinter would shift slightly backwards. A wider wheel in a way acts like a running block. More friction, more grip, higher acceleration which in essence is what drag racing is about.
surface area gets neglected from the coulomb friction model taught in high school or freshman physics because with linear and isotropic materials (ie steel) it doesn't matter that much. visco-elastic materials like rubber have a pretty significant pressure dependency on grip. more contact area means lower average pressure for a given total normal force and hence higher grip. that's why slicks work. or why ultra high performance summer tires have pretty minimal tread features. or why larger tires can be made to work better.
Bigger tires typically means you can run more tire pressure while having the same footprint area preventing tire shake and maintain control of the dragster. You guys are great over there at donut one of the main reasons I have learned so much about different stuff in cars
Engineer/particle physicist here. The reason that surface area isn't accounted for in the equation for friction coefficients is based largely on the fact that epstein didn't kill himself followed by the numerical representation of pi which is roughly 3.14159
Physics question answer: the road and the tire are both uneven/imperfect surfaces which mean they come into contact with each other at multiple points over the contact surface area (explained by the peaks and valleys example in the video). Each one of these points experiences the full force of static friction. Since each contact points independently experience their own frictional force, it creates a cumulative effect across the contact patch of the tire, which is why "more surface area equals more friction".
Agreed! If the contact points were perfect rectangles between two surface of homogeneous properties, the area of the contact surface wouldn't matter. With how the road is, and how compliant the rubber is, the larger the tyre, the more chance it has to find a spot of high friction. I'm assuming you can see this effect in reverse with rolling friction (in which theoretical tyre size would not have an effect but real tyres do)
Everyone thinks AWD and Subarus are some kind of magic in slick conditions. They're not, the just have a boost to acceleration in low traction situations, which MIGHT help you get unstuck. It does nothing for braking or turning.
@@Ididerus it’s more stable than rwd at least. But other than that, it’ll skid like any other car. I’d argue fwd is slightly safer in slippery conditions anyway in terms of handling.
A contact patch gives more grip for a few reason. When you add weight to the rubber its grip does not go up in a 1 to 1 fashion. Rubber has a diminishing result when more weight is added exponential at first then tapers. So if you go over the max weight for a set contact patch and material your grip will stop increasing because the rubber will tear and deform. Also the rubber has a mechanical key with the road as it drives over much like you talked about in your video and the coefficient of friction doesnt equate for the keying on the road where the rubber can grab the road and has a mechanical bond at a microscopic level. The rubber also adheres to the road in a small way depending on compound. Since were talking about wider tires and race tracks I will also assume stickier tires. At a molecular level the tire adheres to the road surface slightly and more stickiness means more gripyness. As the rubber moves to the road surface that is robbing energy which means more grip by turning kinetic energy into heat.
I'd say for the tires, and by what I remember from physics classes, the formula doesn't have the width component in it simply because it is considered as if the tire was touching the ground on a line, aka, something that has no area (Because it is a line of points, and a point has no surface area), whereas in reality, because of weight and different forces applied on the tire, it will flatten and the contact patch will go from a line to a rectangle.
I felt like the dumbest smart guy or smartest dumb guy when you asked the grip question and automatically said "something about a coefficient" and I was not entirely wrong 😂
This chanel has taught me more about my car than any class I have taken and has saved me so much money from getting riped of at dealerships. Thank you!! ALSO DO MORE OVERLOADING STUFF! Nissan frontier would be nice! Or the AUSTRALIAN Offroading seen
Right, to expand on this, each tire will have its own value for Mu. A wider tire will have a higher coefficient of friction when compared to a thinner tire that is made of the same material, has the same diameter, and is inflated to the same pressure. So wider drag tires will have a higher value for Mu, giving a greater frictional force overall for a vehicle of the same mass (since the Normal Force is just the mass of the vehicle multiplied by acceleration due to gravity). Inflation pressure and diameter will also play a role in changing the Mu value for a tire.
Jerry - The maximum friction between the tire and the pavement is determine by your equation Friction = mu * Fn, where Fn is determined by the weight of the car. However, when the drag car launches off the line, there is torque from the axel that rotates the wheel. This creates a new horizontal (tangential, not normal) force, and therefore a shear stress (Horizontal Force * contact area) between the tire and road. A higher area gives the tire more ability to translate the rotation of the wheel into forward motion of the car without having the tire break free due to exceeding that stress limit (i.e. burn out). Increasing contact area reduces the stress, and therefore area is very important. T-shirt?
Coulomb's law of friction is only relevant when two perfectly flat surfaces meet. For example stiction isn't accounted for, as are many other real world changes. As noted, the ground isn't actually smooth in the case of road surfaces and rubber tires, and so Coulomb's law does not hold. In this case there are many factors to be noted. Bigger tires (at the same pressure) don't actually increase the size of the contact patch, with the same weight (pounds) and the same pressure (per square inch) the size (square inches) has to be the same. However by making the contact patch shorter and wider there is a number of benefits. The main being due to the rotation of the tire. Viewed from above the forwards motion of the tire is always changing. The leading and trailing edges are slower, whilst the middle is full speed. This means the leading and trailing edges are both being dragged along the ground slightly to bring them to the same speed, whilst the middle (with the most weight) is having to fight that. A shorter contact patch means less of that effect, whilst wider doesn't reduce grip in any way leading to a net benefit. This pulling also stretches the tires and heats them, whilst producing losses (one part of the reason higher pressures provide less drag). Another factor to remember is that the grip of tires decreases as weight is increased. Or In Coulomb's law, the Mu decreases as weight increases (leading to a higher force overall, but tending to decrease in a curved way similar to a log x graph). This is due, in part, to micro tire deformation into the cracks. It takes little force to get a moderate amount of keying into the cracks and bumps producing grip (due to the asymmetric lateral forces on the bumps as the tire slips - tires MUST slip to produce grip). However as force is increased there is far less to gain squeezing into the final part of the gap, and this leads to less improvement. Reducing the pressure increases the size of the contact patch, and so the force pressing into the cracks is reduced and spread out leading to a net gain of grip. This is also why equal weight on all tires produces more grip than high body roll or high anti-roll bar settings. There's a lot more which goes into it, but those are two of the most important factors as to why bigger tires and/or lower pressures helps with grip. Other fun tire examples, the asymetric grip of a contact patch through corners (outside half of the tire travels further than the inside half producing a twisting moment we see often as bikers lose grip under braking). As a motorbike rider rather than car driver there's a few motorbike specific fun things such as the changing contact patch as the bike leans producing many effects. But there are still fun effects for cars such as an upright car tire with a strong lateral force bending the rubber below the rim seen quite vividly in 50s F1 which produces the need for camber. Or the optimal tire yaw (ie sideslip angle) changing as the weight on wheel changes leading to race cars setting the outer tire to turn more tightly than the inner tire, or "anti-ackermann" to produce slightly more grip. Lots of interesting and cool effects go into tires once we get past the myth of Coulomb's law with respect to tires.
Hmm, I haven't heard of striction before but what you say does ”sound” realistic. The attention to detail is impressive and I happen to agree with it all including the last part about it being interesting and cool
So, there are a few reasons why, first of all larger tires have a lower mass distrubution per area unit therefore allowing for lower presures wich lets the tire to flex more and adapt better to the road. Second, having more area is good for heat dissipation and a lot of heat is generated in those types of race.
Answer: Ff and Fn are perpendicular to each other. Fn is perpendicular to the surface while Ff is parallel to the surface. Unless you get into small dimensions where entrenching occurs, two (same material) objects of equal mass with different proportions will share the same frictional coefficient. A tire with the same mass that is twice as tall and half the width of another tire while sharing equal mass will have the same frictional coefficient. (assuming everything else is equal) It's easier to increase the mass of a tire by widening it rather than making it taller. When you increase the surface area, the pressure is spread out more due to them sharing an inverse relationship. So a lighter and wider tire would have less friction then a narrower heavier tire. (assuming everything else is equal). All in all, surface area "doesn't matter". If you increase surface area you spread out the same amount of force over a wider area which balances out and has no change on the frictional coefficient. However if you increase the mass AND surface area, you can increase pressure between the tire and the surface giving you more 'grip'. Wider tires also have other benefits with relation to temperatures, etc. *Note that those Racing Slicks are not just bigger, they're more massive (heavier) 😊 I'm not an engineer and I'm not 'smart'; I guarantee someone will provide a much better explanation with proper equations to support them. I don't currently know the shortcuts to type "Ff" and "Fn" properly lol. (But I'm trying to get a free shirt here Dammit!...) ***Edit*** smh... I'm reading other comments that are making me doubt myself here... there are other factors I didn't consider but will hold steadfast... I really want a damn shirt... and a sticker.......and some jungle nuggets......
So about the last question you asked here is the answer engine produce torque force which has to be transferred to the ground by tyres so if u have more torque than the friction between road and tyre, the tyre will start to lose traction because the force exerted on tyre is more than the friction available from tyre to ground so this will lead to wheel spin which is for bad any type of launching a car or bike so in order to increase the friction of tyre and ground we use wider tyres but still you can increase grip of tyre by choosing a softer rubber but there is a limit, so hence we use wider tyres to create more friction between tyre and road than the force exerted by the engine.
In a nutshell, tire also creates a longitudal force on a side of a crease in asphalt which helps propell the car forward, because it adds to a friction force... THIS WAS A FRAGMENT TO GRAB YOUR ATTENTION SO YOU MIGHT CONTINUE READING My take at answering the question in the end of a video: First of all, mind that the simple equation people learn at school is formulated for rigid body on rigid body, flat surface on flat surface friction, which is just not the case. This is also why specifications on some tires might state that their friction coefficients are bigger than 1, which makes no sense in "usual" circumstances. Now, "flat surface" here is as in "flat to the eye or touch", because friction itself is ocurring only because of imperfections in both surfaces interacting with each other, down to a scale of two atomic grids (which we consider absolutely rigid) grinding on one another. Now, my thoughts about why bigger contact patch tends to mean better traction are next: As it was said in the video, soft rubber fills the gaps in the rough surface of the asphalt. Gaps have profile in a plane parralel with a tire rolling direction too. This is drawn at a picture at an attached link, with forces marked. In a nutshell, tire also creates a longitudal force on a side of a crease in asphalt (which is marked as Fadd as in force that is added), which helps propell the car forward, because it adds to a friction force of a tire on a horizontal part of a surface. And as this force can vary greatly depending on the depth of a crease, how much it is filled with rubber, the angle of a crease's wall, tire temperature (or any other parameter) in a given point, and other things i probably didn't mention, it is important to have larger contact patch so you can cover as much creases in the road as possible. Ultimately, this forces are limired only by the car's weight(because only weight keeps rubber in a crease), not the friction coefficient, as the rubber creates vertical force escaping the crease under rotational forces of the wheel, BUT this vertical force is not equal to car's weight because all the movement it provides is so small it only deforms the tire, not lifts the car up. Covering more creases in the road actually adds up (up to a point, indirectly limited by car's weight, of course), rather than resulting force being equal to the highest achieved one, because each point of a tire holds only a part of car's weight. So, increasing the contact patch of a tire actually improves this added force(but not the friction), which combines with the force of friction and propells the car faster. This explanation also doesnt account for adhesion, as i am not competent to speak about it occuring here (means i know nothing about it). This also only explains why linear acceleration of a car requiers wider tires (as for dragsters), but huge width also has a lot of benefits to cornering. idroo.com/board-suDimwSIQk Nobody will ever see or read this, i am almost sure, and it surely wont reach guys from DONUT. But it might.
To throw an analogy at you to see if I understand, you're basically saying that rather than the classical model of a rigid body on a rigid body. The softness of the rubber allows it to deform sufficiently to push against the peaks of the roughness of asphalt similar to a sprinter against a starting block? Is that a about right? If that's the case then we're dealing with a force that behaves like friction, in that it retards movement in the direction of travel, but in fact comes from something more akin to normal force.
@@bentreece1187 While your analogy is correct as i see it, my whole comment might be not. What i described here might seem like "friction after friction", and the mechamism is similar, but at this scale it is more like gears which rotate each other with interlocking teeth rather than friction, just that weight is what keeps the gear's teeth in place. The way i see it, because friction utilises microscopic imperfections, and this process utileses macroscopic, they have no relation to each other because one cannot influence the other. To me, what i described and what friction is really don't seem like the same thing just because when we talk about friction we talk about two surfaces (means no major geometry, just planes), with imperfections in them being small in depth relatively to the area ot the contact, and size of them being very regular. Both of these conditions are not quite true for what i described. So yes, this is only possible because of the softness of the rubber, it's ability to change macroscopic geometry to "become a matching gear" to rough surface ot the asphalt. And gears sure (as far as i understand) can work without friction. Take the metal-plated wooden wheel from the video for example. Not only it's fricion coefficient is lower, it has no means of grabbing these macroscopic geometry in the road. Unless it has teeth or spikes, than it can take advantage of these added forces by burying them in the road, again, without any relation to friction. So, yet another analogy, but the roles are reversed - here the earth is soft and the wheel is rigid, but the mechanics is the same - they act like two solid gears. Regarding your last sentence: friction itself is a manifestation of a normal force in microscopic scale. Mechanism is really similar to what i described, but without deformation there is no "burying one thing into another". Just imagine two very, very fine iron files that you put one on another and tried to pull them apart, - they would resist because ridges in them bump into one another.
Imperial bitches...2/32 is 1.59mm which is way lower than tire manufacturers say tires are yet safe.usually when tire is worn down to its last 3mm roughly 3/32 of an inch tire is done. In my country summer tires need to be at least 2mm or 1/16 of inch and winter tyres(real studded ones or Nordic winter tires without studs) needs to be at least 3/32 of inch I usually ditch old ones when thread is worn down to 4mm or 1/8 of an inch
@@jkarra2334 Do they not have jokes or sense of humor anywhere else in the world but U.S.A.? Apparently not. 2/32 and 1/16, is the same. We were aware of this. Its called a joke.
Same I was disappointed when he passed through it in the beginning as if they never even existed 😢 but the low ridin chicanos still rock those on their classic old school low low riders....what's up esé, what set chu claim 😎
μ has surface area in it. In general the coefficient of friction is just a rough approximation. It's a model for how friction would affect an object and models have limitations. As you have said, road conditions can be varied, so to estimate we just take averages. Different tire widths act differently as well. Differently shaped contact patches and all that.
Mall crawlers endangering all of us with their high center of gravity making emergency turns suddenly dangerous. I'd love to see a moose test with a modified vs stock modern day 4wd suv or truck.
@@goawayihavecommentstomake1488 because braking and turning cause imbalance in the car's weight distribution. This can lead to understeer and/or higher chance to oversteer once you turn, and I don't think it is easier to manage than having the car balanced. This is why you should learn defensive driving.
@@goawayihavecommentstomake1488 Think about it like this, there's a car reversing out of a driveway right in front of you, do you hit the brake; Potentially slowing you down and increasing the amount of time you're behind this car? Or do you turn sharply to avoid a collision.
Maybe someone already said it, but it expands your contact patch. A larger circumference allows a larger ‘flat’ spot on the bottom. And a wider tire just makes the other dimension of the patch longer. It’s an increase in surface to surface friction over a given space.
Answer to Uncle Jerry's question: I've wondered about this a long time. My guess is that the wider tire allows for more opportunities for the best possible coefficient of friction to exist between a given contact patch of tire and asphalt. The coefficient of friction is a point property, meaning that it changes to some degree at every point that it is measured. So more contact, better chance of a pebble or particularly bad surface to not ruin that coefficient. Although I'm sure there are a lot of other contributing factors
Combined with the tire squatting when the drag car launches the car essentially shifts into a lower gears due to the diameter of the tire getting smaller.
He covered contact patch. I'm thinking it may have alot to do with the aspect ratios allowing the tire to deform and hold that contact patch, if the tires were a 170/20 on some 22s the tire could be the same width and height as some drag radials but the aspect ration makes a world of a difference.
The footprint of the tire does not affect traction. That's why he asked the question: the equation for calculating friction does not include a surface area (footprint) component.
Also, as it turns out, choosing bigger tires (in either diameter or width or both) doesn't substantially change the footprint. You just end up with less of the larger tire in contact with the surface below at any given moment. And there's your hint for the correct answer!
I've studied suspension design and grip theory of race cars in engineering school. If you double the weight on the same tire/suspension package, your grip does not double, it's slightly less. Same goes the other way, if you halve the weight, you have slightly more than half the grip. Friction coefficients are VERY general in the assumptions that go into them for general calculations. Realistically, the surface area statistically gives more peaks to grip, and if your compound is optimized for the weight and temperature, it will engage more of these peaks to increase mechanical grip. Edit: Doubling the weight and not resulting in double the grip is due to shear forces exceeding the limits of the material itself at a microscopic level.
18:40 engineering student here: it’s more of a probability problem than a statics one. wider tires just increase the chances for the tire to make contact with the road, allowing the tire more opportunities to get the full coefficient of friction in a certain time period.
True, but it also has to do with the local strength of materials. Shear forces from the torque can break off small pieces of the track or tire, but with that pressure spread over a larger patch, this becomes less likely to happen (still partially probability, but the local probability for this issue is also lowered)
Ans: wider tyres exerts less pressure, so the company can use softer compound without compromising wear and tear, and that softer compound provides more grip.
19:08 because there is a greater area, more force can be applied at any point on the tire. Pressure=F/A so A*P=F. A greater area at the same pressure will yield a greater force, so mu increases, thus increasing the friction force.
Would you count "the coefficient of friction between the cars tire and the road surface" as a definition of grip? I need to know if I win my imaginary $100
@@skrimper Well no. Yes, the magnitude of the friction force that is grip is a function of both the coefficient of friction and the normal force. But that's just that, the magnitude. Do you even understand Newtonian physics? A body need a force to be applied to it for a resulting acceleration to alter it's otherwise straight motion. That's like saying a human isn't a mammal, it's only an organism. Like you aren't wrong, but you aren't right either. If there was no force applied, then the car would just continue gliding in a perfectly straight line no matter how much you turned the steering wheel. You would also not be able to accelerate or brake. Would you not consider that a lack of grip?
Keeping the average density of the tire material constant, increasing the size of the tire means increased weight, and increased weight means increased Normal Reaction force. Now, more normal force means more friction and hence a better grip.
Este es uno de los episodios más interesantes e informativos que he visto aquí en este canal, gracias Jeremías!!! 😎👍 (Mi hijo de 13 años y yo de 50 años, somos de Venezuela y vivimos en Orlando, FL y nos encantan tus videos)
a wider tyre only distributes heat better, it doesn't increase grip. Cause after all, the weight of the car will put pressure on a bigger tyre surface area and that will push the tyre into the ground less, so you will actually have less grip.
There's an elaborate answer to this but I think the point is that frictional force does not depend on the apparent area of the surface in contact but actually requires points of actual microscopic contact to be there which is why wider tyres which allow for a wider contact patch thus more points that are to be in contact thus allow grip to suffice in various hard turning situations etc
Bro straight did a JarJar impression while doing the Vulcan Salute from Star Trek and said Star Wars movie 🤣 Great video by the way! I love learning how things are composed and how they work
The coefficient of grip isn't stable but it decreases greatly as the vertical force applied to the tire increases, so you'll need to spread the same amount of force in a larger area
Answering the engineering question: there are 2 main reasons: 1) Wider tires under a given (moderate to high) load will last longer than similar narrower tires (for a variety of reasons). Wider tires let you run softer compounds without excessive wear. 2) Race tires actually adhere to the track (like tape) when broken in. This isn't simple friction anymore and increased surface area does give more traction. (Like wider tape = more sticking force). I've heard you can stick a kart racing tire to the ceiling if it's hot off the track.
Basically, you want an evenly spread load across your tires. If you make your tires wider, it becomes easier to achieve this. A larger contact patch on the ground will allow you to accelerate more quickly, stop in a shorter distance, and handle higher cornering speeds.
my answer: my theory is that more area means that it evens out the force between the road and the tires as if the friction force is as an breaking point until it slides or loses grip. :D
Using wider tires has two benefits. First one is that with more contact patch the force and the weight is distributed over a larger area and allows to use a softer compound. Softer rubber means a higher coefficient of friction that allows more grip and also it deforms better on the asphalt irregularities. Second and less obvious one it has to do with racing compounds. If you ever touched a racing car tire or a sportbike tire when warm you can see that it's sticky kinda like a bubble gum. This means that a wider tire has more sticky area. It's like stiking a 1kg weight to the ceiling or the wall with a small piece of tape or with a much wider tape. The wider can hold more weight.
Isn’t the frictional coefficient just between materials. Is a number that gets plugged in to another equation to determine traction that would take into account surface area
The Tuatara DID set a speed record, which it has to exist to do. The Devel 16 hasn't been seen driving more than the average city speed limit, and news on its development is extremely limited.
I'm just an average auto mechanic and race fan but here goes. Drag racers run wider and larger diameter tires to maximize the contact patch, the same reason they use "Wrinkle wall" slicks, so it lays a huge flat patch of soft rubber on the pavement that conforms to those peaks and valleys in the pavement and also as they increase speed the sidewalls stretch so the tire width narrows to reduce rolling resistance and the overall outside diameter increases greatly to change the effective gear ratio as the car picks up speed, mainly because the top classes of drag cars only have one gear ratio.
The coefficient of friction in tires is not constant like the simple situations we study in school. The coefficient of friction in tire rubber decreases with increased surface pressure. Larger tires, greater area, reduced pressure, greater friction. They don't teach that in the physics books
There seems to be a lot of incorrect answers on here. Let me further explain. The simplified formula for the force of friction we learn in undergraduate physics fails for tire compounds. In theory, a 30 ton Mack truck with locked wheels should stop as quickly as a Honda accent with locked wheels. Which we know is not true. In that formula the force of friction is irrespective of the area. ( It also doesn't consider the transition between static and dynamic but that's a different topic ). For tire compounds, the coefficient of friction changes with the surface pressure ( not air pressure ). The simplified formula assumes the coefficient of friction to be a property between two materials and surface roughness. But in reality for tire compounds surface pressure matters, therefore the area of the contact patch matters.
Coefficient of friction only takes into account the resistance to sliding of two materials with perfectly flat surfaces. Like you mentioned with tires conforming to the surface, a larger contact patch adds more peaks and valleys that can apply force in a horizontal direction. It may only be a fraction of a pound per little valley/groove, but the more you have, the more it adds up. On top of that, you get into footprint mechanics where the slip angle of the tire isn't consistent through the length of the contact patch. If you make the contact patch longer instead of wider, you get a less optimized slip angle through the length of the contract patch. A wider tire adds the same area (for increased grip from the above behavior) but also keeps the slip angle through the contact patch more consistent/optimzed, resulting in higher grip. That's one of the reasons old, classic race cars on skinny tires always looked like they were drifting through corners. Excellent video dude. Keep up the great work!
It's because of a property of rubber called " viscoelasticity". So as the load on the contact patch of a tire increases, the pressure increases (because pressure is load over area). And as the pressure increases the resistance to frictional shearing of the rubber decreases and this cause causes the coefficient of friction of the rubber to decrease. This happens because it gets more rigid and loses it's capacity to deform with the road. So if you have a car with a strong engine and a narrow tire, the pressure on it will get too big when you increase the load while accelerating and that will make the rubber get more rigid, causing the coefficient of friction to get smaller and the tire will have less grip on the road. That's why race cars and dragster have wider tires.
Modern man is not the man who goes off to discover himself, his secrets, and his hidden truth; he is a man who tries to invest himself in something beneficial for the future.
After watching several UA-cam tutorial videos about trading I was still making losses until Mr Salvador started managing my investment now I make $10,567 weekly
As a dragster tire spins, forces cause its circumference to increase and its width to decrease. Effectively turning it into a narrower tire/contact patch.
Answer: coefficient of friction is great for two flat surfaces, but the peaks and valleys in pavement are no longer simply slipping across the surface instead becoming trapped. It's like sliding down a slide vs sliding down some steps with the same coefficient of friction. The slide will freely let you slide to the bottom. The stairs will punish you as you hit every single one of them on way down. Having a wider tire allows for more of the tire to become caught in the 'stairway' at times where grip is needed.
I actually asked the same question to my Dynamics professor a couple weeks ago. it's because Mu isn't a constant. Mu concentrates all the factors that go into two surfaces gripping each other all into one term. If Mu were to be expanded you would see that it depends on surface area in contact, material properties, external conditions, etc. In most cases where the friction equation is used, you can assume that Mu is correct within a certain tolerance. in the case of car tires though, there's a lot of factors that cause Mu to vary wildly and so in this instance the friction equation is used as an approximation at best. Love the vid
Asked my dynamics prof the same thing when I took it haha. The other factor is that the traction a tire produces does not actually increase linearly with the vertical loading. Essentially, the coef of friction decreases as the stress in the tire increases. This means that lowering the initial stress in the tire(larger contact area) will produce a higher tractive force under the same loading(the loading ceiling before mu decreases is raised). That is especially true in high downforce applications, but there is still significant load transfer from cornering.
@@tristanhanley8741 oh nice! Thanks! I’m majoring in aerospace and dynamics is kicking my ass so I’m glad to hear the same thing from someone else haha❤️
Took the words right out of my mouth..I should get the shirt 😜
Yep same exact story for me when I was taking those courses 10 years ago. Me being a gearhead helped in some areas but that was one where I was at a definite disadvantage in terms of having to ignore or unlearn some preconceived notions and mental shortcuts for exam. My instructor brought up pretty much the same as yours as well as pointing out that for the sake of exams and theoretical calculations you're always assuming a perfect interface, but of course that isn't the case in reality even on a prepped race surface, and by going with wider tires you can think of it functionally as if you're casting a broader net to achieve that optimal surface to surface interaction.
@@tristanhanley8741 So would that make the equation a f''(x) of the frictional equation, similar to how acceleration is just the second derivation of position? or maybe its the 3rd derivation such as jerk is? Thats my initial guess.
I love this episode, it brings me back to science garage with Bart. "Don't tell my wife." Lol
“The only part of the car that touches the road”
My lowered shitbox: *Frame proceeds to hug the ground*
Please tell me you bought it like that
@@sufferr2914 I actually did
@@twostrokeproductions757 thank god
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@Leonardo Santuario thanks man. I appreciate it
Actual Tire Engineer here: the reason why you can get more than 1G grip and the reason to run wider tires on a race car has to do with shear strength!
When the tread rubber goes into the peaks and valleys of the road surface, your extra grip comes because you have to physically shear off that portion of rubber to move the tire off that spot, the hot tread rubber has penetrated into the grooves & crevices in the road surface so it tears off rather than slides across. That’s why burnouts and donuts leave black marks, it’s rubber that was sheared off. So why wider? Because as you put heat into rubber, it is easier to shear, so a wider tire distributes the heat better but also has more individual peaks and valleys to shear pieces of rubber off.
My quiz for you Jer: how does a tire keep the wheel off of the ground?
Why doesn’t the wheel just squeeze the sidewall down until it is touching the road like pinching a balloon? You can compress the sidewalls by hand, so why don’t they just squeeze out of the way when the car is loaded on it?
This makes a lot of sense. I had a feeling it was to do with shear strength and immediately though of increased area therefore reduced stress, however I quickly debunked myself because Fz = P*A and obviously the pressure and weight on the tire are assumed constant therefore the area does not change amount, just shape. Could the fact that the contact patch become wider and less long with a wider tire also help with grip because more of the area is contacting fresh concrete, not rubber filled "dirty" concrete? The explanation on local heat leading to lower shear strength makes lots of sense!
because of the tires air pressure. and a flat tire can never go below atmospheric pressure you would have to vacuum it out
As was explained: in addition to the frictional force, the tire is also pushing itself off these small peaks in the road. This is not a frictional contact but simply a "stuff pushing itself off other stuff" contact. Normal force is directly transferred between the tire and road in forward direction.
A wider tire is the only option to increase the quantity of little mountains the tire can push itself off and therefore increases the overall amount of grip.
The mu value for grip is just a good enough approximation for normal everyday (I.e. Not drag racing) use.
Sorry for lacking some words. It's really hard to explain this stuff in a foreign language
on top of tire construction and so fourth a balloon is made to stretch a car tire is not a drag slick is closer to a balloon concept as it starts out as a wide tire and the higher the speed it grows taller reducing width to gain diameter it is also used as a gearing aid i could go on and on
on top of all of this sorry one last thing a wider tire makes up for a larger tire in diameter and its really the end of the story there its to keep the tire from having to be 40 inches tall to keep a contact patch on the ground the same as a shorter tire that is wider carry on
I love Jeremiah, he's got to be the BEST at explaining techy things all in layman's terms while being fun. Great presenter. I come back every week for all Donut's videos, but he's my favorite to watch.
Mechanical Engineering and a Masters in Biomedical Engineering. So he has a knack for it.
He wastes too much time making useless jokes and not being precise to the point.
@@shrujanamsyama9940 Don't need to take everything seriously, it lightens up the mood. Plus, he gets around to most points eventually
@@IgnitionP Not really. I came for studying science but this guy just irritated me. Most geeks like me would not like these types of jokes as they are too obvious & cheap
this episode is giving me some science garage vibes lol (still miss that show 🥲)
samee
holy shit a verified channel that isn't a bot as one of the top comments
It's because of that show I started watching donut.
Bring back Bart!
What happened with Bart??
I can't wait to watch this in college as apart of my course
Wat course will u be doing?
I swear the last 6 months of watching donut makes me feel like I'm halfway through a technicians course
@@tinashemoalusi8920 mechanics just started in September and all ready seen a past donut video
exactly what im doing rn
Seriously these videos are great for learning how to apply engineering principles
Engineer here. The equation Friction = (coefficient of friction)*(Normal Force) doesn’t tell the whole story.
As the normal force increases, the coefficient of friction actually goes down slightly. This explains why body roll causes the car to lose grip. More weight is put onto the outside tire, but the coefficient of friction of that tire is now lower than what it was before, which means that the total force that stops you from sliding decreases.
The reason why you want wider tires is twofold. First, wider tires can absorb and dissipate more heat that narrow ones. So if you’re generating lots of heat from racing for example, narrow tires would get too hot and overheat, causing decreased traction.
Secondly, if the same force is distributed over a larger area, the pressure the tire feels goes down. This makes the coefficient of friction go up, since each tiny section of tire is feeling less weight on it, because there are more sections to distribute that weight.
TLDR; more weight, lower coefficient of friction. Distribute that weight over more surface area, coefficient of friction goes up. Higher coefficient, higher grip.
Looks like we found the smarty pants
So instead of thinking of it as force pushing it down a better way to think of it is the pressure pushing it down?
@@Stevethe11th sort of. The formula is still F=mu*N, but think of mu as a function of N and surface area (and temperature)
Yes and no. Normal force is a multiplier of mass. So a heavier vehicle will have more traction than a lighter vehicle on the same tires. It just takes more energy to make it accelerate and decelerate.
this is the first correct answer I've seen. good job
side note, you shouldn't confuse body roll and weight transfer. while they're related, they aren't the same thing.
second side note: a bigger tire isn't always faster. while it can give you more grip by allowing you to run a lower pressure for the same load carrying capacity, it also means more mass to accelerate out of the corner.
On the topic of wear bars, one thing I think is cool about the Continental ExtremeContact DWS tires (which are great by the way) is a built in wear indicator. There's a D (dry), W (wet), and S (snow) imprinted in the tread blocks that will wear out in reverse order. When the S is gone, it means they aren't ideal for snow anymore. Then the W wears out, meaning they no longer are good in the wet. Then the D, obviously meaning dry traction is no longer ideal. It's just a cool little system they have that simplifies reading what stage your tread wear is at. Slick bit of kit if you ask me.
I agree this is brilliant. I wish it was standard across tires.
If Jeremiah taught a high school science class, those kids would learn so much!
At the same time, allowing Jeremiah to influence young minds..
I know what you mean 😉
That's not want the world needs. If he was just a science class teacher only a few would learn. Now we ALL get to learn and he influences young minds all over the world.
Jeremiah would be the teacher from the "Whoever threw that paper..." vine
ua-cam.com/video/_09XHdZhtSI/v-deo.html
please be my physics teacher Jerry, you would be such an improvement
wider tires aren't making any single point stickier they're just allowing a larger distribution of the forces. lower force over a given point will result in less slip.
To expand, the amount of force per square inch is less such that the rubber won't deform as much and fail at the contact point.
As well as being able to use a softer compound with similar tread life
To put it in even simpler terms, for a larger tire you'll get a larger contact patch. And while the contact patch is horizontal, the shear force is what matters here. So, the actual ability to grip comes from not just the theoretical friction force, but also the ability for both surfaces to remain in place. If you have a smaller tire with the same forces, it's more likely that the tire or ground will start to break down. This can be seen most closely with the grooves made in roads by semi trucks, as they are heavily loaded and are able to quite literally push the asphalt away as opposed to simply pushing off of that asphalt.
On top of all that, many of these tires are also made to bond to the asphalt. More patch means more bonds, and more bonds means more resistance to sliding. This translates to a higher real world friction coefficient.
This is all too complicated for me. Someone please explain to me very simply, why does a road bicycle tyre (think tour de france tires, 2-4cm wide) have such good grip, even though it's so slim?
14:10 wider channels between lugs (particularly on more offroad focussed tyres like mud terrains) actually help the tyres to self clean when driving through mud and sand so that when the next part of the tyre becomes the contact patch it isn't full of slippery mud. All terrain tyres tend to get filled with sand or mud which does help on soft sand but is completely useless in mud as they don't self clean. The wider channels also help the lugs to deform around rocks when they are let down to give the tyre as large a contact patch as possible when driving over rocks and the like.
I feel like Jeremy is feeling more and more like the family, and it's great to watch.
Love the Donut family.
That's what they are
It's Jeremiah, or jerry
jerry's my favourite
I read this in Vin Diesel's voice
Dom approves
Until you and grandma are walking home together.
The reason why drag racers have wider tires is to introduce more points for the tire to enact force on the "peaks" of the road surface. In an introductory physics course most of your teachings and understanding is on a single point of contact, or particle. So the friction equation F_f = \mu * F_n, can be scaled according to however many particles, or instances of contact you have. That's also why drag racers use softer tires, and often deflate them, so than can introduce more instances of contact to the road/track surface. For example if you have a tire so small, where it only makes contact with only one peak in the road surface, even in a heavy vehicle, the force of friction will still be relatively small compared to it's weight. It's like have only one one person push a brick wall, but if more people push the wall, eventually the wall will topple. You also cant forget there are two different types of friction, static and kinetic. Static, for when an object is usually at rest and trying to move; and Kinetic, for when an object is usually moving, and is trying to stop. Coefficients of static friction are typically smaller coefficients than kinetic friction, meaning it's harder for the weight (which is "equal opposite" of normal force) to act on the tires regards to get gaining Grip.
-UCF Aerospace Engineering undergrad
Also, I love you guys!
static coefficient > kinetic friction
Its the same thing we do when we go mountain biking, less air more surface area more speed and control downhill 🤙🏽
Thanks for the info
You won that t-shirt for sure!
In layman terms, more surface area to contact with... just as intuition would say. Maybe there is nothing that accounts for a definite area in an equation somewhere, it's essentially still the same thing, in a roundabout way. More points of contact literally translate to a bigger surface area. That's quite literally what an area is, a lot of discreet points next to each other. Deflating a tire just increases the contact are with the road as it sags more under the same load. I understand what you say but it seems the question is more philosophical than describing reality.
This is not exactly true, theoretically in the simple friction formula area does not matter. Even if a mack truck only contacted one peak, the available friction force would be the same. The answer to the question is the coefficient or friction is not constant with tires compounds. The coefficient itself is inversely proportional to surface pressure. That's why the simple physics formula you learn in your undergraduate generally fails when you consider tires. With the simple formula there is no reason that a truck takes any longer to stop it than a motorcycle. ( Mechanical engineer )
Anyone else miss the old B2B where James would get an interesting car and go into detail about it from front to back. Love the series that Jeremiah does though!
I want both
Just go watch Doug's channel ;)
I miss the LIGHTNING!
I like the ones where James cries because he's moved emotionally. Realy men aren't afraid to show emotion. Love ya James!
Actually, not trying to throw shade, but James is my least favorite presenter, because he is always trying too hard to be over-demonstrative. It seemed very natural in the early vids years ago, but now days it comes off as trying too hard. Where Jeremiah comes off much more naturally most of the time, but he also pushes into that "James Zone" from time to time. But a lot less than James actually does. Either way, I like all of them. It's just in varying levels.
The answer is Hector is going to be running 3 Honda Civics with SPOON engines. And on top of that, he just went into Harry's, and he ordered 3 T66 TURBOS, with NOS. And a MOTEC exhaust
Lol Spoon with Turbos😆🐤
F&F
I never understood the last part, MOTEC never made exhaust systems lol
@@WhatZitTooYaaa i think thats kinda the whole point of that line. Dismt want too include any real companies other then nos because nos is a brand and its well shown off in FF so they either sponsored or idk. The spoon engine is real but its not actrually called a spoon engine. I think its a very specific honda crate engine(not made by honda) and their like 30-40k and dont exactly make alott of power but their made too handle more power then any axle you can fit in those cara coupd handle😂
when Nolan is just drilling at the table during the "Mo Powa Babeh" Ad. LMFAO
If we’re talking about Top-fuel dragster’s they use an extremely low tire pressure (I think 5-10psi)so they can use the affect of acceleration on the low pressure to change the circumference during acceleration and use this affects as a sort of gear box, when the car the launch’s the circumstance is the biggest it’s gets and along the run the circumference gets smaller to change the supposed gear ratio through the tires.
Absolutely fascinating stuff.
(I think top fuel dragsters officially only have 2 gears in they’re gears box)
Zacharia Weisman : You have the getting bigger vs smaller thing backwards. It starts off small then at speed it increases diameter due to centrifugal force. It does in effect change the final gearing.
Him throwing the vulcan hands up while saying "messaa loved the new star wars movies" in Jar Jars voice made me die a little inside lol. Our beloved childhood franchises are so lost.
About lost my mind over confusing the two.
The Spock / Jar Jar crossover film needs to happen now! Com'on Disney and CBS play nice for just this one time!
ua-cam.com/video/_09XHdZhtSI/v-deo.html
Beloved garbage
@@recreant359 Are you dumb or just saying all star wars is garbage?
"You could be eating your Jungle Nuggets. And a guy could have a seizure. It could happen. It's why I go there."
...me too
wtf
Jeremiah is truly a man of culture.
That place is real?
@@danielaguilar1125 Yea it is, I haven't been there in a while
Tire Test Engineer here. I will say this was a great and informative video, love these from Donut Media! Tread pattern design is not just for looks though, that does come into play some, but the shape of the tread pattern will be driven by tire noise too. A passenger car tire is designed to minimize road noise while a wet race tire is designed for maximum water evacuation. Having tested about every tire type, a wet race tire does the best job at evacuating water from the contact patch, but they are extremely noisy tires in both wet and dry surfaces, this is comparing slicks and wets with the same compounds and constructions. The average customer would not want a tire as loud most of the wet race tires.
Keep up the great content!
Tyre test engineer, go test tire, stop wasting time on internet typing long comments
@@Kottam_Yallawa if you aren't here to learn about tires, feel free to go look at pictures of cats and shut your brain off, since you obviously don't value it
@@CorvusCorone68 says the person who got offended by random internet comment 🙂
Answer: wider tyres increase odds of getting the maximum friction the surface has to offer. Also lowers pressure per unit area which lowers overall wear.
I think your right!
I am not a engineer but I did read the other comments and they look right when I looked what they said on google. Basically the reason why larger tires give more grip is because the world is not perfect and there is sometimes gaps between the tires and the ground, and making them larger gives you more chances to touch the ground. Though in a perfect world a small tire and a large tire would have the same amount of grip.
no that's not actually the case. it's because Mu in the friction equation is a variable not a constant and surface area plays a huge role in determining the value of Mu
Uh, depressuring your tires increases wear, the sidewall isnt meant to take excessive loads when under aired, you can risk bubbling or debeading because your tire isnt keeping its shape
@@pleasedontwatchthese9593 The most used Racing tires are a slick, meaning no tread. Just a giant contact patch. Formula 1 uses either slicks in dry conditions and a lightly treaded pattern in wet conditions. If it were a perfect world we would all be running slicks optimizing grip to a n almost 100% degree of contact.
@@ultimatum117052 He's not talking about the air pressure of the tire, to my understanding he is refering to the same pehomena that makes snowshoes work. Larger footprint = weight being distributed on a larger area.
If you have a 5 square inch contact patch and your ''car'' weighs 100lbs, you apply 20 lbs per inch on the ground of pressure,
if you now have 10 square inch contact patch but the same weight, you now apply 10 lbs per inch. so in that sense, the tires would last longer. If that makes any sense lol
“Goodyear was arrested for owing some guy money”
Me who had intoxicated ox riding: my disappointment is immeasurable and my day is ruined
That cat in the tiger costume and sunglasses(around 14:55) was extremely adorable
That's funny. So was the burp (2:42)!
A week ago I realised I need new tires and kept researching the best options for best possible grip and this helped me more than anything
I just got the continental DWS06 tires and it's rained twice since then I've purposefully tried to lose traction to compare to my old. I highly recommend them they are very grippy
@@user-gk2cg2th9h had a look and they come in just the right size, fairly cheap too!!! Cheers
A lot of people have already attempted to answer this, and I might just get lost among the other thousand comments, but I'm learning about this in a physics class this semester so I thought I might take a crack at it. The reason that F_f (force of friction) is not dependent on surface area is that when surface area is larger, the weight force (F_g) is spread out more across the surface area. Essentially, larger surface area means less weight per unit of area. However, the reason that drag racers use larger tires (I think) is that on a drag course with a treated surface that has whatever sticky substance on it, friction is not the only force acting between the tire and the road.The adhesion (ability to stick to other things) of the sticky substance is very high, and when there is more surface area on the tire, there is more surface area for the tire to adhere to the sticky stuff. However, I don't know too much about drag racing so I may be wrong about sticky stuff.
That's all makes sense, but that leads to the question why normal sports cars or race cars have so wide tires?
Why are the Corvettes tires so much wider than a Honda civics tires?
I have a feeling it's about the tire wear. for example, if a 1in by 1in section of a tire can only take a certain amount of force then on a skinny wheel you will exceed the limit of the 1in by 1in section. but on a wide tire, the tire doesn't exceed the maximum amount that section can hold because there is physically more surface area for the tire to hold.
frictional coefficients are not constant between two materials. there often is a pressure dependency. for rubber a higher pressure means a lower coefficient of friction and less grip.
adhesion is one of several friction mechanisms present in tires. drag tire tread compounds have friction coefficients much higher than 1.
@@bolt5564 I think that’s more to do with use cases. Wider tyres are a huge draw to fuel efficiency and even some power, so unless the benefit of extra grip sometimes isn’t worth what you’re losing
Wider tires are able to use softer compounds, therefore have a lower coefficient of friction. So a drag car has extremely soft and wide tires with a really high coefficient of friction. As the tires get narrower, the coefficient of friction goes up due to the compound getting harder.
In regards to cornering, the wider the tire, the stiffer the side wall leading to less rolling in the tire.
s/o to this channel. i’ve never been all that into cars, but you guys make it so easy to understand & it’s so enjoyable
When creating a good compound for acceleration, softer compounds are favoured however an issue with softening the compound is that it will no longer support the weight of the car. To alleviate this, widening the tire and potentially using different compounds in different areas, along with stiffening the sidewalls helps to increase the weight the tire can support as well as improving cornering performance as the tire also experiences less roll. This widening gives a larger contact patch with the surface also, again helping to even out irregularities in a surface, increasing stability and grip.
Correct. You beat me to it.
My (hopefully) educated guess for the last question regarding the absence of surface area in the formula of friction force goes like this. It does not influence the linear movement grip, but it highly improves cornering grip, the same way in which wider bodies improve cornering stability. A good way to visualize these scenarios is to take some exaggerated versions of the extremity-scenarios: imagine a car with bicycle wheels. When cornering, a narrow tire will bend towards the inside of the corner (relative to the rim), moving the contact patch towards the lateral side of the tire, and rendering the highly engineered middle of the wheel useless, since it loses contact. A wider tire will have a much harder time bending like that, since it is supported by forces further apart, thus maintaining the contact patch in the area the tire is designed to have it. Same reason why low profile (hope that's the correct terminology) tires will perform better when cornering on smooth surfaces: bending is limited. A seemingly counter example would be the high profile tires of Formula 1 cars, but they are smooth everywhere, anyway, so even if the contact patch moves to one side, the road will still see the same type of tire surface, and would behave the same (assuming same chemical composition on said surface). That's my two and a half cents, hope I'm not way off. If you got this far reading my long comment, might as well leave me a like to show that you agree ;) Great content my dudes, love your vibes and appreciate your powerless communication which makes you so much more relatable and enjoyable. Peace out.
Edit: Uziel Lavine's answer seemed pretty persuasive as well, for the microscopic aspect of it. As a macroscopic view, I still think my point stands.
I see people posting their backgrounds, I'm a physicist engineer. :)
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This is true but he does also ask in relation to ‘drag racers’. They generally don’t require cornering at high speeds as they are straight line cars. From what I remember hearing from my mechanic mates, a wider tire profile for drag cars are generally to benefit ‘off the line’ response. This is also why the back tires are much wider than the front tires. To accelerate, the engine must apply force to the driving wheels (which with most drag racers, is RWD). When you accelerate, weight transfers from the front of your vehicle to the rear.
My mate likened it to a sprinter launching from running blocks. The sprinter will ‘launch’ faster because the running block is providing a resistant, otherwise theoretically the sprinter would shift slightly backwards. A wider wheel in a way acts like a running block. More friction, more grip, higher acceleration which in essence is what drag racing is about.
surface area gets neglected from the coulomb friction model taught in high school or freshman physics because with linear and isotropic materials (ie steel) it doesn't matter that much. visco-elastic materials like rubber have a pretty significant pressure dependency on grip. more contact area means lower average pressure for a given total normal force and hence higher grip. that's why slicks work. or why ultra high performance summer tires have pretty minimal tread features. or why larger tires can be made to work better.
drag racing doesn't have corners. Bigger tire= more grip in drag racing.
Bigger tires typically means you can run more tire pressure while having the same footprint area preventing tire shake and maintain control of the dragster. You guys are great over there at donut one of the main reasons I have learned so much about different stuff in cars
But old cars with thin tyres have like 80 psi whereas modern tyres have 30.
Engineer/particle physicist here. The reason that surface area isn't accounted for in the equation for friction coefficients is based largely on the fact that epstein didn't kill himself followed by the numerical representation of pi which is roughly 3.14159
Physics question answer: the road and the tire are both uneven/imperfect surfaces which mean they come into contact with each other at multiple points over the contact surface area (explained by the peaks and valleys example in the video). Each one of these points experiences the full force of static friction. Since each contact points independently experience their own frictional force, it creates a cumulative effect across the contact patch of the tire, which is why "more surface area equals more friction".
Agreed! If the contact points were perfect rectangles between two surface of homogeneous properties, the area of the contact surface wouldn't matter. With how the road is, and how compliant the rubber is, the larger the tyre, the more chance it has to find a spot of high friction. I'm assuming you can see this effect in reverse with rolling friction (in which theoretical tyre size would not have an effect but real tyres do)
I'm fairly certain this is the majority of the answer. Friction does not go up with surface area, but mechanical grip DOES.
Very informative I use to change tires and now mostly alignments and good tires makes me happy
I would love to see B2B on “World of Outlaws” Sprint Cars
I laughed really hard seeing the Subaru hit that pole in the snow when talking about grip coefficient and water. Just perfect
Everyone thinks AWD and Subarus are some kind of magic in slick conditions. They're not, the just have a boost to acceleration in low traction situations, which MIGHT help you get unstuck. It does nothing for braking or turning.
@@Ididerus it’s more stable than rwd at least. But other than that, it’ll skid like any other car. I’d argue fwd is slightly safer in slippery conditions anyway in terms of handling.
They dont turn for crap in the snow. Until it finally goes into snap oversteer 5 seconds after flooring it
@@Ididerus the stock tires are summer tires and people think they are rally cars
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A contact patch gives more grip for a few reason. When you add weight to the rubber its grip does not go up in a 1 to 1 fashion. Rubber has a diminishing result when more weight is added exponential at first then tapers. So if you go over the max weight for a set contact patch and material your grip will stop increasing because the rubber will tear and deform. Also the rubber has a mechanical key with the road as it drives over much like you talked about in your video and the coefficient of friction doesnt equate for the keying on the road where the rubber can grab the road and has a mechanical bond at a microscopic level. The rubber also adheres to the road in a small way depending on compound. Since were talking about wider tires and race tracks I will also assume stickier tires. At a molecular level the tire adheres to the road surface slightly and more stickiness means more gripyness. As the rubber moves to the road surface that is robbing energy which means more grip by turning kinetic energy into heat.
I'd say for the tires, and by what I remember from physics classes, the formula doesn't have the width component in it simply because it is considered as if the tire was touching the ground on a line, aka, something that has no area (Because it is a line of points, and a point has no surface area), whereas in reality, because of weight and different forces applied on the tire, it will flatten and the contact patch will go from a line to a rectangle.
I felt like the dumbest smart guy or smartest dumb guy when you asked the grip question and automatically said "something about a coefficient" and I was not entirely wrong 😂
This chanel has taught me more about my car than any class I have taken and has saved me so much money from getting riped of at dealerships. Thank you!!
ALSO DO MORE OVERLOADING STUFF! Nissan frontier would be nice! Or the AUSTRALIAN Offroading seen
Mu in the friction equation is a variable not a constant and surface area plays a huge role in determining the value of Mu
Right, to expand on this, each tire will have its own value for Mu. A wider tire will have a higher coefficient of friction when compared to a thinner tire that is made of the same material, has the same diameter, and is inflated to the same pressure. So wider drag tires will have a higher value for Mu, giving a greater frictional force overall for a vehicle of the same mass (since the Normal Force is just the mass of the vehicle multiplied by acceleration due to gravity). Inflation pressure and diameter will also play a role in changing the Mu value for a tire.
Jerry - The maximum friction between the tire and the pavement is determine by your equation Friction = mu * Fn, where Fn is determined by the weight of the car. However, when the drag car launches off the line, there is torque from the axel that rotates the wheel. This creates a new horizontal (tangential, not normal) force, and therefore a shear stress (Horizontal Force * contact area) between the tire and road. A higher area gives the tire more ability to translate the rotation of the wheel into forward motion of the car without having the tire break free due to exceeding that stress limit (i.e. burn out). Increasing contact area reduces the stress, and therefore area is very important. T-shirt?
You're right, the width of the tire is used while calculating the friction force created by the amount of torque
Coulomb's law of friction is only relevant when two perfectly flat surfaces meet. For example stiction isn't accounted for, as are many other real world changes. As noted, the ground isn't actually smooth in the case of road surfaces and rubber tires, and so Coulomb's law does not hold. In this case there are many factors to be noted. Bigger tires (at the same pressure) don't actually increase the size of the contact patch, with the same weight (pounds) and the same pressure (per square inch) the size (square inches) has to be the same. However by making the contact patch shorter and wider there is a number of benefits. The main being due to the rotation of the tire. Viewed from above the forwards motion of the tire is always changing. The leading and trailing edges are slower, whilst the middle is full speed. This means the leading and trailing edges are both being dragged along the ground slightly to bring them to the same speed, whilst the middle (with the most weight) is having to fight that. A shorter contact patch means less of that effect, whilst wider doesn't reduce grip in any way leading to a net benefit. This pulling also stretches the tires and heats them, whilst producing losses (one part of the reason higher pressures provide less drag).
Another factor to remember is that the grip of tires decreases as weight is increased. Or In Coulomb's law, the Mu decreases as weight increases (leading to a higher force overall, but tending to decrease in a curved way similar to a log x graph). This is due, in part, to micro tire deformation into the cracks. It takes little force to get a moderate amount of keying into the cracks and bumps producing grip (due to the asymmetric lateral forces on the bumps as the tire slips - tires MUST slip to produce grip). However as force is increased there is far less to gain squeezing into the final part of the gap, and this leads to less improvement. Reducing the pressure increases the size of the contact patch, and so the force pressing into the cracks is reduced and spread out leading to a net gain of grip. This is also why equal weight on all tires produces more grip than high body roll or high anti-roll bar settings.
There's a lot more which goes into it, but those are two of the most important factors as to why bigger tires and/or lower pressures helps with grip. Other fun tire examples, the asymetric grip of a contact patch through corners (outside half of the tire travels further than the inside half producing a twisting moment we see often as bikers lose grip under braking). As a motorbike rider rather than car driver there's a few motorbike specific fun things such as the changing contact patch as the bike leans producing many effects. But there are still fun effects for cars such as an upright car tire with a strong lateral force bending the rubber below the rim seen quite vividly in 50s F1 which produces the need for camber. Or the optimal tire yaw (ie sideslip angle) changing as the weight on wheel changes leading to race cars setting the outer tire to turn more tightly than the inner tire, or "anti-ackermann" to produce slightly more grip. Lots of interesting and cool effects go into tires once we get past the myth of Coulomb's law with respect to tires.
Hmm, I haven't heard of striction before but what you say does ”sound” realistic. The attention to detail is impressive and I happen to agree with it all including the last part about it being interesting and cool
How lonely, are you?
@@Kottam_Yallawa Not lonely, but educated. Likely an engineer or engineering student. Most of us know that basic information.
So, there are a few reasons why, first of all larger tires have a lower mass distrubution per area unit therefore allowing for lower presures wich lets the tire to flex more and adapt better to the road. Second, having more area is good for heat dissipation and a lot of heat is generated in those types of race.
Answer:
Ff and Fn are perpendicular to each other. Fn is perpendicular to the surface while Ff is parallel to the surface. Unless you get into small dimensions where entrenching occurs, two (same material) objects of equal mass with different proportions will share the same frictional coefficient.
A tire with the same mass that is twice as tall and half the width of another tire while sharing equal mass will have the same frictional coefficient. (assuming everything else is equal)
It's easier to increase the mass of a tire by widening it rather than making it taller. When you increase the surface area, the pressure is spread out more due to them sharing an inverse relationship. So a lighter and wider tire would have less friction then a narrower heavier tire. (assuming everything else is equal).
All in all, surface area "doesn't matter". If you increase surface area you spread out the same amount of force over a wider area which balances out and has no change on the frictional coefficient. However if you increase the mass AND surface area, you can increase pressure between the tire and the surface giving you more 'grip'. Wider tires also have other benefits with relation to temperatures, etc.
*Note that those Racing Slicks are not just bigger, they're more massive (heavier) 😊
I'm not an engineer and I'm not 'smart'; I guarantee someone will provide a much better explanation with proper equations to support them. I don't currently know the shortcuts to type "Ff" and "Fn" properly lol. (But I'm trying to get a free shirt here Dammit!...)
***Edit*** smh... I'm reading other comments that are making me doubt myself here... there are other factors I didn't consider but will hold steadfast... I really want a damn shirt... and a sticker.......and some jungle nuggets......
Drag tires are extremely light weight.
In fact, they weigh about half the amount that a street tire of the same size would weigh.
So about the last question you asked here is the answer
engine produce torque force which has to be transferred to the ground by tyres so if u have more torque than the friction between road and tyre, the tyre will start to lose traction because the force exerted on tyre is more than the friction available from tyre to ground so this will lead to wheel spin which is for bad any type of launching a car or bike so in order to increase the friction of tyre and ground we use wider tyres but still you can increase grip of tyre by choosing a softer rubber but there is a limit, so hence we use wider tyres to create more friction between tyre and road than the force exerted by the engine.
In a nutshell, tire also creates a longitudal force on a side of a crease in asphalt which helps propell the car forward, because it adds to a friction force...
THIS WAS A FRAGMENT TO GRAB YOUR ATTENTION SO YOU MIGHT CONTINUE READING
My take at answering the question in the end of a video:
First of all, mind that the simple equation people learn at school is formulated for rigid body on rigid body, flat surface on flat surface friction, which is just not the case. This is also why specifications on some tires might state that their friction coefficients are bigger than 1, which makes no sense in "usual" circumstances. Now, "flat surface" here is as in "flat to the eye or touch", because friction itself is ocurring only because of imperfections in both surfaces interacting with each other, down to a scale of two atomic grids (which we consider absolutely rigid) grinding on one another.
Now, my thoughts about why bigger contact patch tends to mean better traction are next:
As it was said in the video, soft rubber fills the gaps in the rough surface of the asphalt. Gaps have profile in a plane parralel with a tire rolling direction too. This is drawn at a picture at an attached link, with forces marked. In a nutshell, tire also creates a longitudal force on a side of a crease in asphalt (which is marked as Fadd as in force that is added), which helps propell the car forward, because it adds to a friction force of a tire on a horizontal part of a surface. And as this force can vary greatly depending on the depth of a crease, how much it is filled with rubber, the angle of a crease's wall, tire temperature (or any other parameter) in a given point, and other things i probably didn't mention, it is important to have larger contact patch so you can cover as much creases in the road as possible. Ultimately, this forces are limired only by the car's weight(because only weight keeps rubber in a crease), not the friction coefficient, as the rubber creates vertical force escaping the crease under rotational forces of the wheel, BUT this vertical force is not equal to car's weight because all the movement it provides is so small it only deforms the tire, not lifts the car up. Covering more creases in the road actually adds up (up to a point, indirectly limited by car's weight, of course), rather than resulting force being equal to the highest achieved one, because each point of a tire holds only a part of car's weight.
So, increasing the contact patch of a tire actually improves this added force(but not the friction), which combines with the force of friction and propells the car faster.
This explanation also doesnt account for adhesion, as i am not competent to speak about it occuring here (means i know nothing about it).
This also only explains why linear acceleration of a car requiers wider tires (as for dragsters), but huge width also has a lot of benefits to cornering.
idroo.com/board-suDimwSIQk
Nobody will ever see or read this, i am almost sure, and it surely wont reach guys from DONUT.
But it might.
To throw an analogy at you to see if I understand, you're basically saying that rather than the classical model of a rigid body on a rigid body. The softness of the rubber allows it to deform sufficiently to push against the peaks of the roughness of asphalt similar to a sprinter against a starting block? Is that a about right? If that's the case then we're dealing with a force that behaves like friction, in that it retards movement in the direction of travel, but in fact comes from something more akin to normal force.
@@bentreece1187 While your analogy is correct as i see it, my whole comment might be not. What i described here might seem like "friction after friction", and the mechamism is similar, but at this scale it is more like gears which rotate each other with interlocking teeth rather than friction, just that weight is what keeps the gear's teeth in place. The way i see it, because friction utilises microscopic imperfections, and this process utileses macroscopic, they have no relation to each other because one cannot influence the other.
To me, what i described and what friction is really don't seem like the same thing just because when we talk about friction we talk about two surfaces (means no major geometry, just planes), with imperfections in them being small in depth relatively to the area ot the contact, and size of them being very regular. Both of these conditions are not quite true for what i described.
So yes, this is only possible because of the softness of the rubber, it's ability to change macroscopic geometry to "become a matching gear" to rough surface ot the asphalt. And gears sure (as far as i understand) can work without friction. Take the metal-plated wooden wheel from the video for example. Not only it's fricion coefficient is lower, it has no means of grabbing these macroscopic geometry in the road. Unless it has teeth or spikes, than it can take advantage of these added forces by burying them in the road, again, without any relation to friction. So, yet another analogy, but the roles are reversed - here the earth is soft and the wheel is rigid, but the mechanics is the same - they act like two solid gears.
Regarding your last sentence: friction itself is a manifestation of a normal force in microscopic scale. Mechanism is really similar to what i described, but without deformation there is no "burying one thing into another". Just imagine two very, very fine iron files that you put one on another and tried to pull them apart, - they would resist because ridges in them bump into one another.
2/32 of an inch? I would have sworn it was 1/16 of an inch.
Well you'd be wrong then! It's 2/32, which is totally and completely a very different number than 1\16!
I was gonna say that but, ya beat me to it. Mustve been that core math. Lmao.
Imperial bitches...2/32 is 1.59mm which is way lower than tire manufacturers say tires are yet safe.usually when tire is worn down to its last 3mm roughly 3/32 of an inch tire is done.
In my country summer tires need to be at least 2mm or 1/16 of inch and winter tyres(real studded ones or Nordic winter tires without studs) needs to be at least 3/32 of inch
I usually ditch old ones when thread is worn down to 4mm or 1/8 of an inch
@@jkarra2334 Do they not have jokes or sense of humor anywhere else in the world but U.S.A.? Apparently not. 2/32 and 1/16, is the same. We were aware of this. Its called a joke.
Keeps has to keep sponsoring the show cuz at this point it’s a series
Jerry: tires are the only part of the car that touches the ground
Stance nation : I beg to differ
Yea fuck stance.....
That’s stance/camber gang not rice. Get your stereotypes right.
@@Ontheregz Geez sorry
I thought you will also tell about classic white tires and the history of white-walled tires. =)
Same I was disappointed when he passed through it in the beginning as if they never even existed 😢 but the low ridin chicanos still rock those on their classic old school low low riders....what's up esé, what set chu claim 😎
Less we forget.
He mentioned that carbon makes the tires stronger, UV resistant, and black. That's the whole story isn't it?
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They already made that video. Dig deeper
μ has surface area in it. In general the coefficient of friction is just a rough approximation. It's a model for how friction would affect an object and models have limitations.
As you have said, road conditions can be varied, so to estimate we just take averages. Different tire widths act differently as well. Differently shaped contact patches and all that.
Mall crawlers endangering all of us with their high center of gravity making emergency turns suddenly dangerous. I'd love to see a moose test with a modified vs stock modern day 4wd suv or truck.
Moose Test doesn’t make sense to me… why can’t you brake AND turn?
I think it’s just a name for a stability at speed rating.
I'd love to see the hydroplaning tests with those too.
@@goawayihavecommentstomake1488 because braking and turning cause imbalance in the car's weight distribution. This can lead to understeer and/or higher chance to oversteer once you turn, and I don't think it is easier to manage than having the car balanced. This is why you should learn defensive driving.
@@goawayihavecommentstomake1488 Think about it like this, there's a car reversing out of a driveway right in front of you, do you hit the brake; Potentially slowing you down and increasing the amount of time you're behind this car? Or do you turn sharply to avoid a collision.
Goodyear was arrested for owing some guy in South Philly money. The calmest of the 3 lol.
I was sad this wasn't in the episode. I was counting on you, uncle Jerry.
Maybe someone already said it, but it expands your contact patch. A larger circumference allows a larger ‘flat’ spot on the bottom. And a wider tire just makes the other dimension of the patch longer. It’s an increase in surface to surface friction over a given space.
Answer to Uncle Jerry's question: I've wondered about this a long time. My guess is that the wider tire allows for more opportunities for the best possible coefficient of friction to exist between a given contact patch of tire and asphalt. The coefficient of friction is a point property, meaning that it changes to some degree at every point that it is measured. So more contact, better chance of a pebble or particularly bad surface to not ruin that coefficient. Although I'm sure there are a lot of other contributing factors
The wider tires on a drag car create a larger footprint for better traction
Combined with the tire squatting when the drag car launches the car essentially shifts into a lower gears due to the diameter of the tire getting smaller.
We’re trying to change our ecological footprint for the better here 😓
He covered contact patch. I'm thinking it may have alot to do with the aspect ratios allowing the tire to deform and hold that contact patch, if the tires were a 170/20 on some 22s the tire could be the same width and height as some drag radials but the aspect ration makes a world of a difference.
The footprint of the tire does not affect traction. That's why he asked the question: the equation for calculating friction does not include a surface area (footprint) component.
Also, as it turns out, choosing bigger tires (in either diameter or width or both) doesn't substantially change the footprint. You just end up with less of the larger tire in contact with the surface below at any given moment. And there's your hint for the correct answer!
I've studied suspension design and grip theory of race cars in engineering school. If you double the weight on the same tire/suspension package, your grip does not double, it's slightly less. Same goes the other way, if you halve the weight, you have slightly more than half the grip. Friction coefficients are VERY general in the assumptions that go into them for general calculations. Realistically, the surface area statistically gives more peaks to grip, and if your compound is optimized for the weight and temperature, it will engage more of these peaks to increase mechanical grip.
Edit: Doubling the weight and not resulting in double the grip is due to shear forces exceeding the limits of the material itself at a microscopic level.
18:40 engineering student here: it’s more of a probability problem than a statics one. wider tires just increase the chances for the tire to make contact with the road, allowing the tire more opportunities to get the full coefficient of friction in a certain time period.
True, but it also has to do with the local strength of materials. Shear forces from the torque can break off small pieces of the track or tire, but with that pressure spread over a larger patch, this becomes less likely to happen (still partially probability, but the local probability for this issue is also lowered)
Ans: wider tyres exerts less pressure, so the company can use softer compound without compromising wear and tear, and that softer compound provides more grip.
19:08 because there is a greater area, more force can be applied at any point on the tire. Pressure=F/A so A*P=F. A greater area at the same pressure will yield a greater force, so mu increases, thus increasing the friction force.
Btw pressure is constant because the weight of the car is constant (same weight on each of the tires)
"just stick with us" did not fly over my head Jerry
Would you count "the coefficient of friction between the cars tire and the road surface" as a definition of grip? I need to know if I win my imaginary $100
@Ysabela Bruh what is up with you catfish 🤣 You that desperate for peoples data?
No, that's only a coefficient. Grip is the friction force provided by the tires, which is determined by, among other things, that coefficient.
@@rauldragu9447 grip isn't a force it's a function
@@skrimper Well no.
Yes, the magnitude of the friction force that is grip is a function of both the coefficient of friction and the normal force. But that's just that, the magnitude. Do you even understand Newtonian physics? A body need a force to be applied to it for a resulting acceleration to alter it's otherwise straight motion. That's like saying a human isn't a mammal, it's only an organism. Like you aren't wrong, but you aren't right either.
If there was no force applied, then the car would just continue gliding in a perfectly straight line no matter how much you turned the steering wheel. You would also not be able to accelerate or brake. Would you not consider that a lack of grip?
Keeping the average density of the tire material constant, increasing the size of the tire means increased weight, and increased weight means increased Normal Reaction force. Now, more normal force means more friction and hence a better grip.
Este es uno de los episodios más interesantes e informativos que he visto aquí en este canal, gracias Jeremías!!! 😎👍 (Mi hijo de 13 años y yo de 50 años, somos de Venezuela y vivimos en Orlando, FL y nos encantan tus videos)
Mi mejor amigo es de Venezuela, vive en Miami. Que curioso es el mundo! Saludos!
This is my first video of yours and you’re hilarious… and informative. I actually listened from start to finish. 😂
I have never seen a Star Wars movie in my life, nor a single bit of Star Trek, and even _I_ know you mixed your references, Jer.
He’s literally reviewing me physics for my exams
a wider tyre only distributes heat better, it doesn't increase grip. Cause after all, the weight of the car will put pressure on a bigger tyre surface area and that will push the tyre into the ground less, so you will actually have less grip.
There's an elaborate answer to this but I think the point is that frictional force does not depend on the apparent area of the surface in contact but actually requires points of actual microscopic contact to be there which is why wider tyres which allow for a wider contact patch thus more points that are to be in contact thus allow grip to suffice in various hard turning situations etc
Bro straight did a JarJar impression while doing the Vulcan Salute from Star Trek and said Star Wars movie 🤣 Great video by the way! I love learning how things are composed and how they work
The coefficient of grip isn't stable but it decreases greatly as the vertical force applied to the tire increases, so you'll need to spread the same amount of force in a larger area
Jeremiah: Can you really explain what grip is?
Me: Yes.. it’s friction
Jeremiah: It’s FRICTION!!!
Me: =|
Answering the engineering question: there are 2 main reasons:
1) Wider tires under a given (moderate to high) load will last longer than similar narrower tires (for a variety of reasons). Wider tires let you run softer compounds without excessive wear.
2) Race tires actually adhere to the track (like tape) when broken in. This isn't simple friction anymore and increased surface area does give more traction. (Like wider tape = more sticking force). I've heard you can stick a kart racing tire to the ceiling if it's hot off the track.
I have always wondered about this..🤔
No you haven't
I was just thinking, can you do an Up to Speed on Geo? I wanna find out what it does. Other than rebadging Suzukis, of course... 🤣
like, the Geo Tracker?
@@seanj3667 Yup. Suzuki Vitara🤣
pov: you’re about to buy some tires so donut helps you out and uploads this
The “coefficient” μ is all the factors that create resistance to slippage combined into one including the size of the contact patch.
Interesting. What's more interesting is how the f you managed to get mu in actually text
Whisteling diesel with his charger be like:
Pathetic...
*challenger. Lol he be like tire now go cut cut over go go
Whistlin just altogether proves you don't need tires🤣
Basically, you want an evenly spread load across your tires. If you make your tires wider, it becomes easier to achieve this. A larger contact patch on the ground will allow you to accelerate more quickly, stop in a shorter distance, and handle higher cornering speeds.
The larger footprint resists shearing forces, which in turn allows the car to hook and of course, have a lower 60-foot time.
my answer: my theory is that more area means that it evens out the force between the road and the tires as if the friction force is as an breaking point until it slides or loses grip. :D
Using wider tires has two benefits. First one is that with more contact patch the force and the weight is distributed over a larger area and allows to use a softer compound. Softer rubber means a higher coefficient of friction that allows more grip and also it deforms better on the asphalt irregularities. Second and less obvious one it has to do with racing compounds. If you ever touched a racing car tire or a sportbike tire when warm you can see that it's sticky kinda like a bubble gum. This means that a wider tire has more sticky area. It's like stiking a 1kg weight to the ceiling or the wall with a small piece of tape or with a much wider tape. The wider can hold more weight.
Isn’t the frictional coefficient just between materials. Is a number that gets plugged in to another equation to determine traction that would take into account surface area
The force of friction is equal to mu * normal force. There is no surface area in that equation.
They aren’t road cars if they aren’t real. Looking at you, Devel 16 and SSC Tuatara.
Yeah, the Tuatara WAS real
It was destroyed
The Tuatara DID set a speed record, which it has to exist to do. The Devel 16 hasn't been seen driving more than the average city speed limit, and news on its development is extremely limited.
@@Slimmeyy while yes the tuatara is real and it did complete a top speed run it wasn't going anywhere near as fast as they claimed it was
Comment so good a bot stole it
@@anynonymous1585 I’m aware. But the truth matters more.
I'm just an average auto mechanic and race fan but here goes. Drag racers run wider and larger diameter tires to maximize the contact patch, the same reason they use "Wrinkle wall" slicks, so it lays a huge flat patch of soft rubber on the pavement that conforms to those peaks and valleys in the pavement and also as they increase speed the sidewalls stretch so the tire width narrows to reduce rolling resistance and the overall outside diameter increases greatly to change the effective gear ratio as the car picks up speed, mainly because the top classes of drag cars only have one gear ratio.
The coefficient of friction in tires is not constant like the simple situations we study in school. The coefficient of friction in tire rubber decreases with increased surface pressure. Larger tires, greater area, reduced pressure, greater friction. They don't teach that in the physics books
There seems to be a lot of incorrect answers on here. Let me further explain. The simplified formula for the force of friction we learn in undergraduate physics fails for tire compounds. In theory, a 30 ton Mack truck with locked wheels should stop as quickly as a Honda accent with locked wheels. Which we know is not true. In that formula the force of friction is irrespective of the area. ( It also doesn't consider the transition between static and dynamic but that's a different topic ). For tire compounds, the coefficient of friction changes with the surface pressure ( not air pressure ). The simplified formula assumes the coefficient of friction to be a property between two materials and surface roughness. But in reality for tire compounds surface pressure matters, therefore the area of the contact patch matters.
Coefficient of friction only takes into account the resistance to sliding of two materials with perfectly flat surfaces. Like you mentioned with tires conforming to the surface, a larger contact patch adds more peaks and valleys that can apply force in a horizontal direction. It may only be a fraction of a pound per little valley/groove, but the more you have, the more it adds up.
On top of that, you get into footprint mechanics where the slip angle of the tire isn't consistent through the length of the contact patch. If you make the contact patch longer instead of wider, you get a less optimized slip angle through the length of the contract patch. A wider tire adds the same area (for increased grip from the above behavior) but also keeps the slip angle through the contact patch more consistent/optimzed, resulting in higher grip. That's one of the reasons old, classic race cars on skinny tires always looked like they were drifting through corners.
Excellent video dude. Keep up the great work!
The amount of friction is the same however there is just more of it with wider tires. Thus more friction.
There ya go jer bear
Always a huge fan of this stuff.
It's because of a property of rubber called " viscoelasticity". So as the load on the contact patch of a tire increases, the pressure increases (because pressure is load over area). And as the pressure increases the resistance to frictional shearing of the rubber decreases and this cause causes the coefficient of friction of the rubber to decrease. This happens because it gets more rigid and loses it's capacity to deform with the road.
So if you have a car with a strong engine and a narrow tire, the pressure on it will get too big when you increase the load while accelerating and that will make the rubber get more rigid, causing the coefficient of friction to get smaller and the tire will have less grip on the road.
That's why race cars and dragster have wider tires.
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This intro for any episode will always slap
The most important thing is transforming our minds, for a new way of thinking, a new outlook: we should strive to develop a new inner world.
As a dragster tire spins, forces cause its circumference to increase and its width to decrease. Effectively turning it into a narrower tire/contact patch.
Answer: coefficient of friction is great for two flat surfaces, but the peaks and valleys in pavement are no longer simply slipping across the surface instead becoming trapped.
It's like sliding down a slide vs sliding down some steps with the same coefficient of friction. The slide will freely let you slide to the bottom. The stairs will punish you as you hit every single one of them on way down. Having a wider tire allows for more of the tire to become caught in the 'stairway' at times where grip is needed.
im dying at nolan drilling the table in the shirt ad
It is not just the width, the radius of the tire affects the amount of contact.
Also taking out air out of the tire will make the contact area longer.
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