I bought my car last June from a used car lot so I know nothing about its past history and the dealer had just put brand new sumitomo HTRz tires on it. I have what I think are immitation C5 Z06 wheels in black (17" front and rear, I think 8.5 and 9.5 width but not sure). I love the way they look since the car is also black, kinda a mad max V8 interceptor look. The fronts are 245/45/17 and 315/35/17 rear. The rears look too wide for the rim but haven't had any issues, and Discount Tire put them on so I guess it didn't violate any of their rules.

The problem is these tires (at least the rears) seem to break loose really easily in 1st and 2nd gear, I would expect 315's to grip better but I guess they are dirt cheap for Z-rated tires. Now I am coming from a V6 F-150 with about 200 hp on a good day but even with that no-weight open rear end and cheap goodyear tires you have to really work to spin them when its dry. Maybe its just a nature of having almost double the power and that just the way it is going to be with the LS1. Once I hit about 4500rpm in 1st it almost always jumps right up to the rev limiter which means I shift to 2nd and am lower RPM than optimal. Even in 2nd at times it does the same if the road is not a great surface or something.

I don't want to replace the tires yet because they have barely worn yet and I am cheap but I want to know if there are some better tires in a smaller width (say 275 or 285) that would grip better and look more normal on my rear rims. Fronts look great so I'd probably stick with the 245s up there. Thanks!

 

I had bought those tires for my car when I bought it cuz it had zr-1's on it and also had a 315 out back. Like you said they don't grip very well and you'll find they wear very quick, only have a 160 tread rating I believe. Now I have c5 z06 replica's 17x9.5 all around and have nitto 555 extreme's, the street tire, not the drag radial that's the 555R, and I LOVE them. Much better grip than the summitomos, and wet traction is amazing, and they wear pretty good too. A 315 on a 9.5 width wheel is pushing it, I would go with either a 275 or a 285.