I just installed 12" wide rims on the back of my C6 with Michellin pilot Sport runflats.......345-19s...."Viper Tires". I drag race...not much road racing. I don't think I have any better traction with the wider tires. The original run flats may have been better??? Anybody have any luck with any other tires? I want to keep "run flats" on the car because I take it on long cruises.