i beg to differ. I have seen some VERY fast autocross and track cars on 15's.
the vintage trans am cars, all NASCAR's, spec miata, spec E30, etc all run 15's.
the trouble is, fonding sticky tires in teh siezes we need in 15's, as well as the fact that suspension tuning is trickier with that much sidewall. a low provile sidewall covers a lot of handling ills, and the 17's make it easier to find stciky tires.
