Tire strech impact to aerodynamics and handling 215/65R17 comparison 6,5" vs 8,5" wide wheels

I have pondered also this topic a long time and here is my first take on the matter. I think you actually don`t need convex wheelcovers if your wheel and tire combination is already aerodynamic. You will get much better results by using narrow tire and wider wheel. And by this I dont mean crazy streching.
At the moment my estimation is that for 195/60R18 tire best wheel width is 8x18. That will be 1" wider than recommended max wheel size. I will test
7,0x18
7,5x18
8,0x18
Wheels on that 195/60R18 size to see how it actually performs in moose test, slalom, and 20m grip circle.
Performance gain grip wise in track use should be around 7% in wet and 4% in dry conditions. This would mean in moose test 5 km/h difference in pass speed. If we get half of that I think its a success to use wider wheels. As in track use the gains in time come from straigths when you can keep higher speeds in corners.
More and more manufacturers are moving towards this direction. Here comes the most tricky part. If you use small tire side profile rations you will scrape/get curb rash your wheels almost on first try.
Tesla Model Y stock size 255/45R19 still protects little bit the wheel, but those 255/35R21 performance tires give you no mercy.

[@dennis811]

Great. Thanks for the information!

[@TunekoLtd]

Thanks, more will follow.

[@TunekoLtd]

check also description, there is more details related to this matter.