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)
Explain to me why in the world you would want a 15 wheel on a track car. The focus st-r has 18's. How many cars at the track do you see with 15's?
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