Ramathorn178

Welp I finally secured my wheels a couple weeks ago and now looking for tires on my c5z. Is there any reason I should go with something other than a 295/35/18? I see quite a few people doing 305/30 or even 315/30. In reality the car doesn't see all that much street time and sees about the same track/ course time (5k a year) so figuring might as well get a decent 200tw. Wheel specs are 18x10.5 +62 squared, thanks in advance fam.

SSR Type C

Specs

Cleaning does wonders

Diabolis

The reason to run something other than a 295/35-18 is simple... tire availability. The Nankang CS-R for example - a 200tw, DOT-approved race tire that is the spec tire for one of the race series I run in (not with the Vette though) - comes in a 315/30-18, and a 10.5" wide rim is approved for that specific tire. They revised the compound last year and are now IMHO one of the best 200tw tires.

If you need to drive to and from the track on the same tires, a good race-spec 200tw is all you'll need. Running a square setup also allows you to rotate them front to back so it would be a win-win. As for the width, the difference between a 295 and 305 is minuscule if at all present... some tires run wider and have more square shoulders while others are more rounded, so a 295 from one manufacturer and a 305 from another might have the same tread width. Make sure that a 10.5" wide rim is within the approved rim width for the specific tire model and size you end up getting... that is the primary concern.

When I was using my C5Z as a track car, for the last few years I ran 305/660-18 F and 305/680-18 R Pirelli DH slicks on OEM rears (also 10.5" wide as your SSRs) at all four corners. Professional race teams that run those specific tire sizes are plentiful, and I could get a set of scrubs from a pro team for 1/5th of the price of what they cost new. I am fortunate to live near a track that holds plenty of professional races so I could get scrubs fairly easily. The primary drawback is that you can't drive to and from the track on them, so I mounted a tow hitch on the C5Z and made a custom trailer that took four wheels and a small toolbox. I eventually turned the car into a full race car, but that setup worked for me for a good 5 or 6 years when I only used to do HPDE events. A race slick like the Pirelli DH - even when partially heat-cycled and worn - is still a good ~2.5 seconds a lap faster around my local track than any brand new 200tw tire, so once I tried them there was no going back.

PRE-Z06

I wouldn’t want to run a taller than stock 295/35 up front as even if it doesn’t rub it’s raising the CG, you can keep some rake and run 295/30 up front and 295/35 in the rear with the RE71RS.