[Kroggers]

I would have thought that on a racing car you want the tread and sidewall as stable as possible in a turn?

I have the specifications from Michelin (in Swedish) and they state the following recommendations:

.- 225/40 R 18 wheel size 7,5/9
.- 235/40 R 18 wheel size 8/9,5
.- 265/35 R 18 wheel size 9/10,5
.- 285/30 R 18 wheel size 9,5/11
.- 295/30 R 18 wheel size 10/11,5

In the specifications they say to get best performance you should select a wheel in the middle, so a 285/30 would perform best on a 18x10 wheel.

So with my current 18x8 and 18x10 I could run 235/40 up front and 295/30 on the rear, but Michelin suggest this would not give best performance.