It seems that BSP / DSP BMWs run 285/18s and several have done testing and determined this to be a faster setup than the 255/18. I didn't see a lot of input about 17s because most people are looking for that shorter gearing the 285 offers over a 275/17. If I hypothetically had a BSP S2000, with a 2.2L and an AP1 transmission, 285s would only get me to 65.5ish while a 275/17 would be 67.1ish, and a 295/17 would be 66.6ish, and both a 315/17 and 335/17 would get 67.3mph.

I feel like on the S2000, in BSP trim, there isn't much reason to go to 18" wheels. A 17x10 can be had relatively easily (maybe even 17x10.5), and can probably save 4-5lbs per corner over an 18x10 (or equivalent 18x10.5). Is there something I'm missing? Why does everyone feel like the 18" option is the only way to go?

 

Didn't Uyeda do some testing on the subject? Pretty sure he runs something like an 18x11 with a 285 A6 on his car.

 

Get a DBW ECU and raise the rev limiter.

 

With an AP2...aren't you going to need the taller tire and more rpm? I'd go for the 295 in the back over 285...just my .02.

 

All speeds I mentioned were assuming an 8600rpm redline.

 

On STR tires....what mph is 8600 in 2nd?

 

For an AP2 8600 will get you 63mph, while an AP1 will get 68mph at 9000.

Correct gearing aside, what other advantages do the 18s offer over 17s? I get that most people go with the CCWs, which are modular and if you want to go wider you can just get them rebuilt. But, if you can find the correct width 17 to optimize the tire section width, then I still see it as added weight and cost for no perceived bennifit.

Is it the shorter sidewalls provide better control of the contact patch? I'd love to hear someone who has tested.