Are wide or narrow tyres best for a 4x4?
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- Опубліковано 30 лип 2022
- #tyres #widevsnarrow #4x4tyres
Which is best - wide or narrow tyres? Do wider tyres really give you a greater contact patch than narrow, and if so, how much more? And is the contact patch a different shape? Wide and narrow tyres are also known as fat and skinny, but the concept is the same regardless of the name.
In this video I measure some tyres of different widths and diameters, narrow and wide. and discover the truth about contact patch. And I explain the two types of grip, and how contact patch size affects grip.
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• The wrongness of low p...
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LoL I farm and know.. mud and muddy conditions.. upgraded slightly from 17 x 265-65 to 17 x275-60 for a ford F150 (seven bolter) and it does matter as the tread available is way better and it is wider, but only a half a percent rounder.. and I am still under every speed indicator that the state has put up (just, like 1 mph on the worst). They are more expensive and no real determinable fuel mileage change. Now I come from the day where standard tires where ALL 78-80 aspect ratio and by the mid 70's 60 aspect ratio was about as good as one could get.. and of course I stuck them on my BMW 2002 and the rubbed so that took an extra rubber block to abate that problem..
what...does an f1 car have to do with 4x4ing,,fk all..
you..have never been 4x4ing,,have you.this vid is sht..no one 4x4ing uses a 20'' rim..17'' is max, so you have some side wall & floatation..when let down,,plus, it depends on the ply, of any tire you use, preferably 10 ply.. your vid is bs, .35'' tires are a std 4x4 tire.. if you have ifs or cant fit 35,s. stay the fk home..i dont want to rescue you..ie prado..pos vehicle..the best tire, unless your rock crawling, is a good a/t 35'' bfg..i had dick cepek fc2, for 5 yrs, same tire, no issues, did everything.
BORING..
The Model T with it's narrow tires and wheels did a pretty good job back in the day.
And that is how you fit 4 hours of university lecture material into 20 mins.
Thank you, please share :-)
Those were some very enjoyable minutes too!
@@L2SFBC
I have tall and skinny road tires on a 7,000 lb/ 3175 kg/3.5t 2x4 truck. I need to recover some vehicles due to these recent California floods. If I use tire chains (4"-6" of mud), do I need to air down?
Narrow tires put more pressure on the patch and can dig/sink in mud/sand. Wide tires spread the load and can float on mud/sand.
Narrow tires can get better fuel milage. (Less wind to push and less rotating mass) they also wear faster (given the same compound).
However they can ride and drive better in some cases.
Wide tires are heavier, can be rougher, and may not dig down when needed. Lower the pressure and they may conform around rocks and cracks better. However they are harder to roll like this. Also risks rolling a bead off.
In short. Up to 6 ish inches of snow mud with a solid bottom, narrow wins. Firm road ride, Narrow wins.
Conforming around and absorbing rocks at lower pressures, Wide wins. Mud with not solid bottom...Wide wins. Riding on top of harder packed snow instead of cutting down into it....Wide wins.
In general all purpose off reading where you don't have the luxury or money to change tires. Wide wins.
If you have lots of money to have sets of tires to choose trail conditions.... have at it.
There saved you a bunch of time.
You spelled tire wrong, lol
"wider tires look better on your Instagram" perfectly stated. Great video, great advice.
Glad you think so!
I couldn’t stop laughing when he said that 😂
Finally I understans why military vehicles have tall narrow tires... Thanks !!!
almost like they have engineers to figure this stuff out instead of old mates down the pub
Do they? Typical modern military vehicles have wide tires. Tires from almost a century ago are narrow, whether they are military or not.
The new military with wide tires are for heavy trucks almost not light ones
@@worldengineering7202. Exactly like the old US Army jeeps they were very lite compared to something today like a heavy hummer with armor.
I've been saying this for years, trying to explain it to all my offroad friends. I'm so happy to see this video cause now someone with resources has proved my theory to be correct 100%!! Great topic! Great video! Great job!
Thank you Aaron, would appreciate a share
off roaders are all "Ego".Its big and bad..Bullshit
31x10.5R15 for life
All this theories means nothing compared to experience. A deflated tire works like a caterpillar track. And the soft tyre can easily ride up over the bump created by the tire itself.
@@Deontjie two tyres the same size can behave completely different and have different traction especially on sand.
I'm ex forestry for close to forty years. We had deep mud in Winter and lifeless dead sand in Summer.
We had hundreds of vehicles. Small SUV's right up to heavy off roads 6x6 trucks, 8x8 logging machines and I drove most of them.
NONE had oversize tires, none were lifted, none had winches. We drove knowing the vehicle and to the conditions. Yes, we got bogged, but it was extremely rare. We had a rule "the driver digs it out" so you'd expect absolutely no help, just an audience giving "helpful" advice. 🤣
The only "modifications" we did to some, good brand tires, heavier springs and shockers, bullbars, that was about it.
My own 4x4's over the years were the same and I have driven over some of the remotest parts of Australia.
Very informative video ☺
Thank you! It's really good to get a perspective from operators of diverse vehicles in the same terrain, provide some useful data. I'm guessing your vehicles didn't have ultra-wide tyres either?
The center of Australia was mapped by Len Beadel in a short wheel base landrover with standard wheels on it. He did it on his own without a winch or support vehicles. A lot of people have sat up probably at night or over a long period of time designing these off road vehicles for them to perform to their ability and to be able to manage a lot of different situations.
beadel, & others used corro, to get over dunes ect.. bigger wider tires the better..fact..
@@harrywalker968what is “ect”? Try etc instead, this stands for et cetera. Firstly you didn’t watch the video and secondly narrower tyres have many advantages including contact patch at certain pressures, that is fact. Your statement contains no facts as you haven’t stated in which conditions “bigger wider” is “better”.
This was ridiculously helpful, thankyou. I have a Suzuki Grand Vitara I'm about to upgrade my wheels and tires on (from 226/65/R17 to something on a 16in wheel) and the irony of seeing a GV in this video made me smile a lot!
Purchasing today a set of five 255/80-17 Falken Wildpeak AT3 to replace the 285/70-17 presently clamped to the hubs of my F150. Been pondering this move for a year, now. I'm quite slow.
Thank you Robert! as always for your hard work and for your always in-depth analyses on topics we find interesting and important to our veehickular lifestyles. You are, quite literally, THE MAN. Happy Holidays.
Let us know how you go!
How do you like the narrow tires compared to the wider tires you had? How was road performance and looks to your vehicle?
@@thedetective8150 I changed wheel offset, too, to a +25mm to bring the tread surface back to within the fender vertical (less mud splash), but just. Due to the offset change the taller tire does not rub at all when the previous wheel/tire did slightly which is another bonus. Factory wheel offset was +44mm iirc. Together the look is improved to my taste but the initial impression was underwhelming. The previous, wider tire on a 0mm offset may have looked appropriate for pavement motorsports... and while that is a look I don't mind I prefer the more conservative appearance of the truck, now.
Tarmac/concrete grip is reduced for obvious reasons, then one would add the fact it's an ATIII (it's compound/durometer some have called greasy) which could be the most aggressive tread for any common All-Terrain tire. I run 36 psi Cold (D Load Range tire) and have just one recent very short (5 miles) off-highway run for which we did not air down and drove quite slowly (no greater than 15MPH) due to the exposed rock on a certain forest access road. Traction there is improved and in loose dirt. That's all I have thus far as my off-highway camper trailer/caravan is not quite finished.
@@thedetective8150 I should add that the five ATIIIs purchased are not the 255/80-17 but instead an advertised 34 X 10.50 X R17LT. They measure 33.5" X 10.6" and weigh 55 lbs each.
Sidewall height is also very important. It will affect ride comfort as well as how much you can deflate a tire and still drive.
Indeed!
Excellent information and well presented. That painted tire/paper idea was brilliant. Thank you.
Robert really thorough as usual :) Having spent 20yrs growing rice in NSW on both black and red clay I always removed the standard 750-16 wheels/tyres from the utes and fitted at least 31-10.5's or larger. Much less damage to the tracks/paddocks and when aired down to 10psi made the difference between walking or driving home. In those conditions flotation is everything you only have to see the duals or triples on tractors.
On tractors though its alll about not compacting the ground. Sitting on top off to avoid ruts. Different requirement.
@@timsbike4887 Tim too true, you are correct but gaining flotation on ground with no real bottom certainly helps and narrow say 750-16's definitely cut farm tracks up more than a wider tyre. Each to his own though. :)
Best video I've seen on explaining the differences, very well produced and explained.
Watched this again a second time. Excellent. Thank you Dr Pepper.
Just found this episode. Marvellous to see someone actually collecting facts on this issue. Thanks!
I learnt this from Robert Peppers’ book a few years ago now. Highly recommend.
Narrow and high makes sense to for off roading ! Thanks for explaining !
Robert, Another video that is thoroughly researched, packed with useful information, and expertly presented. You, Sir, are an expert that I trust. Keep up the good work. It is highly appreciated here. Ken Republic, Washington state USA
Thanks for all of that. I had no idea there was so much involved and I am grateful that someone put so much effort into explaining it so well.
You're welcome!
Top notch as usual...now I'll go find your video that talks about the affects of different tread patterns. 🥰
Thank you again for parting with some of your knowledge Robert. Cheers
Very welcome, please share!
This is so good, that very much for your hard work Robert!
My pleasure!
This is the exact reason I stick to OEM size aggressive tire, thank you for your insight.
Always nice to see the research behind the conclusions.
It makes sense.
Thank you, please share :-)
This video was surprisingly informative and well presented. My early 4x4 experience was with militsry M151 jeeps and deuce-and-a-halfs. Relatively narrow tires. Never thought much of them one way or another. I worked for a few years for an employer in the southwest coastal area that maintained a fleet of Blazers , Broncos, and Ram Chargers. OEM tires got replaced with 78- series re-tread snow tires. Handled horrible on the road and weren’t great on the beach sand either. Ironically, some flirtation with Jeep Cherokees with the police package (Goodyear Eagles) were pretty capable on the beach or on trails. Didn’t even have to lock them into 4x4 or low range. The bigger SUVs started getting fat ATs and worked better on the beach although still required 4-low to get anywhere. Suspensions make a huge difference and the Broncos worked better when fitted with Rancho systems. Even worked off road better with OEM wheels and tires. I haven’t done much of any off reading for a while, but am going to rewatch this video and do some serious homework when my Tacoma 4x4 Sport is ready for new rubber. I previously had an Expedition with a Wrangler ATs and once got stuck in my driveway in 10 inches of snow. Of further mention is that early cars such as the Ford Model Ts/As had tall narrow tires. Unless one opted for a Marmon 4x4 conversion, they were all rear wheel drive. Add tire chains in mud or snow and they’d go anywhere. Especially interesting as my late granddad’s generation learned to drive in cars from them teens, twenties,and thirties, and even while living and working in rural areas complete with muddy roads never felt the need for 4x4. Always got around fine with open rear ends and mud grips.
I've been running the thinnest tire I can get, and run a modified steel rim. It ended up being 7lbs lighter than the mag wheels it came with (3.2kg) each wheel, times 6. The performance deflated has been really impressive in sand, snow, mud, washboard, and mountain trails. I decided to go this route many years ago after a heavy snow and my 67 Micro Bus with stock (skinny) tires just sliced through the snow. But this video confirms my other experience of very competent grip when the psi is lowered, and why.
Glad to hear this, thanks and appreciate the comment
What a great video and explanation. Also the additional input on the impact like the rotational weight, that is completely missing in other videos on youtube. Thank you for that content!
Glad it was helpful! Please share :-)
Your analysis & data is extremely helpful. Thank you.
You're very welcome!
Brilliant research mate, thank you!
Very detailed research and excellent explanation. Thank you.
thank you for your hardwork. this is one of the most underated 4x4 chanel
Thank you, please share!
Thank you! I have been looking for a proven and scientific comparison such as this one. Keep up the good work.
Awesome video! Very comprehensive, please do more!
Thanks, will do! Please share :-)
10:29 This is an excellent point that I'm shocked I've never heard anyone else mention before!
What a fantastic, thorough video!
Thanks DKV
Thank you for all your hard work
My pleasure, please share!
Love your approach to off-road performance and hiw you break it down in your videos.. Especially great for those who understand the value of math and physics and want performance over appearance.
I appreciate that, thank you!
Thank you for doing the research and posting this video!
It certainly makes it clear.
Thanks for sharing, it is the most comprehensive video I saw
Glad it was helpful! Please share :-)
Great video, thanks for the work you put into it.
Glad you enjoyed it!
Hi Robert. That was very informative. Definitely going to influence my next tyre choice.
Glad it was helpful! Would appreciate a share :-)
YOU are FANTASTIC.
YOU are GREAT.
THANK YOU Robert. Thank You.
Thanks Terry :-)
Informative video.
One thing I’ve never seen any UA-camr mention is the advantage of fitting the widest tyre you can on a given rim width.
For example if running a 16x8 rim a 285 wide tyre can be aired down lower and have less risk of debeading than a 265 wide tyre.
I use to run 285/70r17 on a 17x9 rim and use to have constant debeading issues at 20 psi.
Since changed to a 285/75r16 (still 33s) on a 16x8 and have aired down as low as 10psi no issues and have never debeaded since.
Are you for real? The extent you take measurements and analyze tires (tyres) is off the charts impressive! What a great video and I have seen a number of your videos on SUV's, road tests, you name it on your channel and they are all equally great. Thank you for all you do!
Glad you enjoyed it!
Amazing video! I have a Jeep Gladiator with Kenda Klever RT 35 x 10.5 inch tires on a 17 x 7.5 wheel and they perform amazing. So many people here in the US run wide tires. They are clueless!
👏🏼👏🏼
Fantastic research job!! And super good info condensation to make a video of just 18min to explain it.
Great
Glad you liked it! Please share :-)
Once again, excellent presentation and fact sharing. Thanks.
Thanks again! Please share :-)
Depends on use. Sometimes floatation helps, sometimes digging deep works better. The one fact you can't argue is that the more air it holds, the higher its load rating can be. So for the rear of my fullsize work trucks, a 305/70 beats a 255/85. Both are 33"
Great info and effort. Thanks sir.
Another tour de force Rober!
Thanks for that...have been in a crossroads of 305/70/17 or 285/75/17 = 33.8, the 305 meant to be wider and 285 taller. This vid helped!
Good video. Educational
We have mostly mud and the best tire is the discontinued
Co-op grip spur 7.50.16
ASPW has been a fan of narrower tyres - his conclusion is from experience, now you laid some evidence down for that. I've always thought that narrower tyres were a better bet for offroad but only theoretical hunch - Thanks for the evidence based insight!
My experience is the same; narrower better, my Defender being a case in point, and I did run wide on my Pajero. Plus, a lot of running driver training and trips. But, evidence works!!!
Super cool video
Great job explaining.
And in a timely matter at that
Thanks please share 👍
Thanks a lot for this extremely detailed explanation. This is tyre-science at it's finest. It's always a pleasure and interesting to watch your videos. So, in general speaking, wide tires on some offroader are mostly for better looks, but not always for better performance.
They can perform better...there's never a 'never'. The main point of the video was not to assume they are always better, and make people aware of the pros and cons.
Wow, it takes a lot to impress me, but . . . you covered basically everything I could think of congrats; VERY good video!
Wow, thanks! Please share the video :-)
I absolutely appreciate this but the sprung vs. unsprung weight comparison slide is reversed. 1kg rotating mass (wheel) should be equivalent to 1.6kg non-rotating mass (cargo).
You have the 1.6kg of wheel weight being equal to 1kg of cargo weight.
Just trying to clarify, otherwise thank you so much for putting this together and delivering it at a great pace!
Awesome work. Thanks
Absolut lecture about tires contact patch. I believe I knew this, but now I understand why. Thank you Robert, great work
Thanks for watching!
@@L2SFBC Im a suscriben now 👍🏻
I’m actually understanding what I was taught years ago. For plow trucks especially, you want the tall lengthier tires, and to do better in softer sand or muddy conditions you’d want wider.
This channel is awesome
Good explanation, and it is entirely consistent with my experience racing enduro motorcycles and touring off-road on adventure motorcycles. I’ve always run narrow tyres in the dirt, they drive through so much better and with the amount of really physical work required to ride a bike through sand you can actually feel a narrower tyre is significantly better. It’s interesting that pretty much all dirt bikes use 21” rims on the front, very “tall”, and most 21” tyres are relatively narrow. Unsprung weight is massively important with motorcycles too. So, intuitively I’ve carried that over to my 4WD setups, basically assuming tall and narrow is generally going to be better, and it was great to get an understanding of the science that supports this in most environments. Thanks.
Thanks, nobody has disagreed and said wide is better; but yours is one of many comments relating what is felt by personal experience to what I show in the video. I never felt my Defender on 235/85/16 lacked offroad capability even in soft sand....so I add myself to that list!
If you ever get a chance to ride a Yamaha TW, which has an obscenely wide tire, in the sand, you may change your mind. The high flotation of the balloon tires keeps you on top of the sand, making riding much easier than on skinny tires.
wow this is gold content! thanks!
Glad you enjoyed it! Please share :-)
Very good and demystify exposition. Thanks.
Some excellent analysis. I've long subscribed to the "longer is better (patch!)" theory, recently putting money where mouth is, in moving from 395/85 R20 to 14R20. I'd also recommend "Defender Mods and Travels" on UA-cam, with videos including "The Best Tyres for Overland Travel". Always plenty of physics based reasoning.
Excellent engineering analysis
Thanks so much!
THANK YOU for being in my court, regarding wider vs narrower tires, even for the street! You have proven, in your contact patch analysis, what I already knew, and proclaimed on an automotive forum that I frequent, and was laughed at on there.
Hah thanks I have the same problem! Please share far and wide...let the naysayers bring their data!
What kills me now days is these people putting these tires with almost no sidewall and rims sticking out beyond the pickup on their vehicles. They really are daft.
Great content. Respect from India
Awesome video.
Thank you.
+1 .. Great informative UA-cam site Herr Robert Pepper. .. Subscribed. .. Cheers, Vail, Colorado
Thank you Michael
I always watch your videos and find them to be very informing. I'm an engineer in the trailer towing industry and love the content you've put out on towing as it makes it easy for me to teach people some of the basics on why things are they way they are, I simply send them links to your videos.
I agree with most of this and was already planning to go with skinnier and taller tires on my current vehicle build. However, there are a lot of other things to consider that don't easily show up in the math. Like how in mud, icy snow, and sand the top layer can be more firm that what's below. Often once you break through that layer (especially "dry" lakebeds and iced over snow) the vehicle will sink to the frame very quickly. Having wider tires makes a very big difference because the skinny tire with a longer contact patch is putting more pressure over an area that's already had pressure from the front of the tire. The wider tire with the shorter contact patch will be covering more fresh ground and therefore be less likely to break through.
Thanks, love it when engineers comment! Yes that's a really good point I hadn't thought of. Which actually goes to the other point of reducing rolling reistance, it's the disadvantage. What I didn't get into was the distribution of pressure throughout a contact patch - it's not even, and I'm not 100% sure if it's the same for narrow/wide. I have a book on terramechanics but it doesn't say, and I can't measure it precisely. However given that the contact patches are pretty close then I doubt it'd make a massive difference.
@@L2SFBC as you mentioned many times in the video, tire dynamics are extremely complex and not fully understood yet. I actually was thinking of how pressure is distributed over the contract patch too. I'm not sure there is equipment that is easily available, but something similar to how a shoe store can find the pressure on foot with a specialized scale but for tires would be a great addition to this tire saga. Thanks for all your hard work!
I am an Engineer myself and agree with extra variables in different conditions, but I think as a general rule of thumb you can use the tall narrow tyres for general better off road performance.
Incredibly insightful. Agree completely
I agree I've been running 11.5 in wide 33 in tires on every terrain and yes they are a little more bulky I mean they're not 35 but I get there a little more bulky. My thing is that in the Sonoran Desert with really deep what some people call Sugar Sand which does not compact at all when you drive on it like beach sand it is always extremely loose no matter what I find 11.5 wide does not make a bunch of rolling resistance the way people say do to drag it really just float right over and I can drive my old Land Rover disco that has under 200 horsepower 30 mph or more cross the softest part of the sand in hundred degree temperature of the Arizona desert and this and you can't even hardly walk through without syncing up to your ankles but when I see smaller or skinnier tires on vehicles they sink right in and can barely move. Also I think optimal contact patch also has to do with the weight of the vehicle because if something is too skinny but weighs a lot it is going to push really hard per square inch but possibly too hard and break the ground likewise if something is to light weights and the tires are too wide it can help the vehicle slide over the surface and not group very well. So I think it really depends on the terrain and the weight of the vehicle and we shouldn't just say skinny is better all the time or for certain Vehicles only it should really be based on the terrain and the weight of the vehicle. So if we determine that the 4000 lb rock crawler does really well with 11.5 wide tires then maybe 12.5 wide is better on a 5000 lb rock crawler for example
what i have never seen anyone do is a comparison between two tyres of the exact same construction and brand, exact same diameter and the only difference being different widths.
I am so glad you put this together Robert. I must point out one critical error in your method however. There is a vast difference in tire sizing between different manufacturers and models of tires. IE 3 265/70/17 tires of different brands will have widely varying tread widths. In addition, different tires will have drastically different behaviors on airing down. I understand that having all sizes in the same brand would be cost prohibitive. In any case, the video is great as are most that you do. Thank you.
Happy you bring this to light. In the U.S. this topic is rarely mentioned since probably the 70's. It is quite difficult to find "tall skinnies". Manufacturers don't even offer you the choice.
Try finding 33x10.50r15 among manufacturers or even narrower. Good luck.
It's a pity there aren't many narrow options. Please share the video :-)
There are things you can do but it takes a little know how. And you in most cases you would have to be willing to change out the Rims to help you achieve what you are looking for. Usually - Flotation sizing is better construction for off-roading. Super Swamper 33x9.50-15 Tire also exists.
right on.. 33's are typically 11.5.
@@g.fortin3228 well you just shop around and/or buy it online. Have them ship it to the shop of your choice. The other thing you can do is to find out where that Brand of Tire(s) are sold, and then have the manager have them in stock for you if you are a regular.
Yes! The douchey truck crowd has ruined the tire market with their douchey super wide and rubber band tread. Seeing a truck with 35s but 26” wheels makes me want to throw up.
I couldn't agree more. Great video.
Bought a used LX470 with 255/70R18 but stock is 275/60R18. This whole world of tires is somewhat interesting.
Terrific video thank you!
Thank you please share 🙏
Very interesting. You put a very credible case for you conclusions.
Graham
I never like to make claims without an explanation and evidence!
This was really eye opening for me 😮
Pleae share and open the eyes of others :-)
I just learned so much more than I was expecting when I searched this question! Also, I'm so glad I did because I was about to go wider to increase performance on my 4x4 but now have learned it's better for me to stay narrow. Thank you!
Glad to help, please share!
Very interesting content!
Firstly thanks for making the effort to do this and the information presented it was very informative.
For a given diameter the length of the contact patch will determine the amount the tyre drops. Wider tyres have shorter contact patches, therefore you can air down more and still have the same wall height. So they have more in reserve, you can air down by a good few psi and still have the same wheel clearance as the narrower tyre. I bet that extra few psi will improve offroad performance way more than any differences in width.
One of the best ways to improve offroad performance is to fit offroad biased tyres, but typically this has a detrimental effect on wet road handling and particularly braking. Something I value greatly as my 4WD is also my family car, having a wider tyre should help according to this video?
Narrower tyres allow you to fit a bigger tyre without rubbing and mods to the car, which is a great advantage IMHO.
PS all my 4WD's have been stock except for fitting a set of AT's of a size similar to stock.
Watched this during work. Made me feel productive
I'm almost afraid to ask what you do at work?
I've run Dunlop 7.50R/16 on my old landrover and my Troopy for 36 yrs, never had a problem off road or on.
Great video. It seems that tire manufacturers should produce more narrow tire sizes than they currently do. At least in the U.S. there are few narrow sizes.
Totally agree. Please share :-)
unfortunately it seems like a trend that's hard to reverse. BFGoodrich seem to be holding on to some "legacy specs"
Wider tires are better for stopping. Most people here in the states don't drive off road.
It's like sports cars on road courses. Wider is better. Then you can run smaller brakes.
@@2dogsf-ing Narrow tires are better for gas mileage and better on snow. They more than hold their own offroad. You have to weigh the pros and cons against your preferences.
@Alan Schreiner I understand your point. I was just saying wider tires are better for stopping. It's like thinking bigger brakes help. Which they do if you're driving a race car. But if you do wider tires it does the same effect.
That's all my point was.
Great video with clear plots on graphs to illustrate your points.
The relationship between tire height, width and tire pressure to contact patch may be just three of the factors to consider when choosing the tire however.
Other possible factors could be:
1. What is the difference between contact pressures per square inch of narrow/wide/high prof/low prof tires?
2. What is the difference in the center of gravity between narrow/wide/high prof/low prof tires and how that affects vehicle stability?
3. What is the difference in centrifugal and centripetal forces between narrow/wide/high prof/low prof tires when stationary and when rolling at various speeds?
4. Also as you mentioned in one of the comments, what is the difference in different areas of the contact patch between narrow/wide/high prof/low prof when stationary and when rolling?
Thanks DocRocker!
1. High vs low profile - see my other video on that subject!
2. CoG - virtually nothing
3. Centripetal - low profile greater due to greater mass & further away from centre, again refer to other video
4. Rolling diameter & CP change to some degree but not significant for 4x4s, it's more a racecar thing.
Simply brilliant!
Many thanks!
Good info. I run a 255/80R17 on my Pajero/Montero which is not the norm in the US but I prefer it.
I'm Dilmar from Escola4x4 Brazil. Your channel is very good! All topics are deep explorated, with a good theory explanation and practical uses. Congratulations! I would like to use your information for my classes...
Hi Dilmar, always open to collaborating with people. Contact me via l2sfbc.com and let's talk.
@@L2SFBC done
Putting narrow tires on my truck this week. From the sound of it I'm going to do just fine 👌🏼
Sounds great!
I've modified my Astro van with 4x4 and a lift - I'm running 235/85R16 LT Falken Wildpeak AT3W's with a full size spare currently mounted under the vehicle (I had to reroute the exhaust over to the passenger side of the vehicle more to make that work) - Off road in mud, sand and over large rocks/boulders the vehicle grips and pulls through everything like a tank, especially when I'm in 4-LOW. I'm very pleased
Good to know - what's an Astro Van?
This explains why I saw no difference in sand driving with my 1979 FJ40 Landcruiser when I went from wide wheels and tires to stock wheels and tires. The stock tires improved the ride and handling. I did the change for cosmetic reasons, but was surprised at the improvement.
Indeed, an FJ40 isn't very powerful so the extra rotating mass would really have sapped power, your suspension wouldn't be designed for the extra unsprung mass, and there would be changes to the geometry of the steering.
It's almost like there were a bunch of engineers who figured out the best size tyres and wheels for that car.
@@L2SFBC Your explanation of the rotating mass factor gives a good insight into why fat tires can be detrimental to performance. Also the demonstration of the contact patch being about the same - just an exchange between the same area distributed on either a transverse or longitudinal plane.
Cool video. Cheers. It would be good to have more of a control in the comparison. E.g use a bfg km3 in 305/70r16, 285/75r16, and 255/85r16.
Also, it'd be great to measure the deformation over objects lateral and longitudinal to the direction of travel.
I think comparing 3 different tyres of identical size would also be interesting.
put some 295/50 r15 on my cj7, never got stuck, good for street, sand, muddy fields, pulled people out with them.
Great informative video! Just want to mention that many rock-crawlers swear by increased unsprung weight, even going so far as to put water in the tyres.
Yes, that's true..the technique is also used in radio-controlled rock crawlers and vehicles like graders and tractors. However, I'm talking here of touring-class 4X4s. I should have mentioned the rock-crawling people, you're right.
@@L2SFBC Is the additional unsprung weight in rockcrawlers for traction or lowering the CG or a combination of both?
@@iffykidmn8170combination of both
We went away from water in the tires on farm tractors in the late 1970s. Chassis weight was a far better option. Reduced air volume was detrimental to tire flex at farming speeds and loads. Friction of soil particles, lug design, tire pressure and case design all effect traction and floatation. (tractor) .
Lot of true in one place, good video.😎😎😎
The greatest issue I'm discovering is that the tires I want are not always available in the narrower widths.
Love the video and research. Did you find correlations with contact patch and vehicle weight? I would expect similar contact patch at a given pressure for different sizes because the vehicle weight did not change, and tires have a similar compliance. (Within the error shown.)
2) An advantage of large diameter tires is running lower pressure to get a larger contact patch when you want. That is helpful when the surface is not solid, like sand, gravel or loose.
3) Contact patch is different on soft surfaces like sand, mud and dirt, because of penetration where the true contact patch wraps around some of the tire. That is an advantage for wider tires because they don't sink as deep for the same contact.
4) Racing vehicles at the end of the video are purpose-built to go fast. Penetration is much less at speed, and traction demands are quite different, so be careful making tire choices for recreation off-road based on those.
Finally, a choice for wide or narrow must also contemplate the terrain. A good tire choice for the desert is probably not the best tire for mud.
Pluses and minuses with everything as you mention. Good job with the video.
Increased vehicle weight will increase the contact patch, yes. However...there is then more weight, and therefore more energy required to move the vehicle, and more pressure on the terrain. So it's better to have a lighter vehicle than a heavier vehicle. In circuit racing this is why aerodynamic downforce is so good - I have explained it here ua-cam.com/video/P3FmufPt0Rg/v-deo.html - because you get the benefit of downforce but no weight. However 4x4s are too slow for any downforce.
The contact patch doesn't change much unless you're talking rock when the entire tyre can rest on a sharp edge. For compression terrains it's more or less the same.
A very comprehensive article and provides great food for thought. One thing that came to my mind when you were winding up and talking about the benefits of each was regarding the weight carried by the vehicle. We trundle down the road in our 4x4s ladden to the hilt on reasonably wide tyres these days. The weights are fairly constant during the whole trip. Is it right to assume that a narrow tyre has a lower carrying capacity than a larger wider tyre when considering the vehicle to be a 4x4? I specify 4x4 because we will be lowering the pressure to do some cross-country driving at some point no doubt. If we were just doing highway driving then the narrow tyres would certainly be better. But for the off-road stuff especially with a fully laden vehicle, perhaps the wider tyres still hold the top spot.
There's not really a correlation between width of tyre and load rating, so narrow is fine for load, just make sure the tyre meets or exceeds the vehicle's placard rating (see other videos where I explain this including the recent Jimny one). Look at the Defender 130, Troopy etc, both run narrow. You will find the lower-profile tyres have lower load ratings though so avoid those. The narrow tyres are lighter so there's more payload for carrying. ua-cam.com/video/xyc8HYzEZPE/v-deo.html
I live in Utah. Home off offroading. We like are tires big and wide. Rock crawler stuff.
Great video, thanks
Glad you liked it!