Originally Posted by rangerbay
I don't know about way more 15 than 16. Forged 16 wheels are lighter than cast 15. The shorter tire is like a lower gear. You do need to wind the car out on the straights, tuck it in for the curves, and with the electronic management on the newer cars, the rotational speed of the smaller outside tire may interfere with the traction control. 16 also have a greater contact patch than a 15, giving more grip and braking. 225/50 seems like a lot of sidewall to me for a track tire.. More sidewall, more squirm. Less sidewall, stiffer.
Again, opinions are like tailholes, everybody has one. I have a Porsche 944 S2 that I do track, and use 16 instead of 18 due to price. If they were the same price, I'd go with the 18. No way would I step down to 15's.
and forged 15s are lighter than forged 16s. shorter tires of any wheel size will indeed lower gearing, hence why most small wheel fitments have larger sidewalls. I agree, that in general more sidewall = more squirm, but most competition tires have stiffer sidewalls to compensate.
also, i call BS on 16 vs 15" contact patch. that has nothing to do with the wheel diameter and everything to do with tire width.
to the OP, why get only 215 wide, when 225 will fit and sitll be a close diamter to stock
you can get:
225/50R15 (this one is shorter, but it's still doable)