315/30/18's on C5 Z06 18x10.5's on Hypercoil 1.4" springs. I've been running 315's for years now on my car, and only now does the passenger side rub on the fender, thats the only issue I've ever had in 4 years and 3 different heights.
You can't deny the 315's. Don't puss out, they fit, it just takes a little creativeness.