The best size is really up to you. Whether you want 16, 17, 18.....is really up to you.
Try picturing it on your car at tirerack.com.
My rims are 18x8 +35 offset. Tires - 225/40/18
It works, no rubbing.
Only thing I hate is the giant wheelgap, which is hideous.
From RRE - Wheels for the track. 16's or 17's.
http://roadraceengineering.com/marctech/2000_9.htm