goshendad

Guys,
I noticed that the ZR1 has 285's on front and 315's on back. My 2009 C6 has 285/35 19 on the rear and 245/40 18 on the front. Would there be any safety issue or reduction in performance if I go to a wider front tire like the 275/40 18? Is this a stupid question? I took the car to the track at Pocono and will be returning in May and want to make sure a tire change on the front will not be a concern by going to a wider tire.

Boomer111

Active handling does have a tire combination factor. others will have to respond as to the math.

I ran 305 rear and 275 front on a straight body C6 and prefer the 285 rear and 245 front. The wider tire up front gave me a heavier front turning experience, which I did not like. the stock combo feels more responsive. No track just street experience.

smurfkiller

many run a 265 front and 305 rear on base c6. i have 245 front and 305 rear. on the stock wheels i think 275 is a lil to wide to run in the front

Drevil

I have been running 265 front and 305's in the rear for 170K miles. Be ready to change your power steering pump. It does not hold up well to the larger tires in the front.

Boomer111

Interesting

Racingswh

You won't want to run a 275/ 40 as the sidewall and overall diameter of the front tire will be too tall. When going with different sizes you will be ok if you keep the front to rear overall diameter relationship similar to stock with the front tires being shorter than the rears.

If grip is what you're after you will find more benefit from going with a different stickier tire compound over going with the same tire you have now with the only difference being it's a wider tire on the same wheel. Same tires only Wider on a fairly narrow rim will sometimes have less grip as it pinches the tire and crowns it in the center reducing the size of the contact patch.

I don't see any reason for you to just put a wider tire on the front. There won't be much benefit if any at all. For best results put stickier tires in stock or if you must then slightly larger than stock sizes. You will be amazed at the difference.

SUCAMILLA U 427

The zr1 sould have 335 in the back not 315 s.

TKOGTO

To my understanding, this is correct on both fronts. (1) the difference in tire height between the front and back needs to stay within ~5% with the rear being taller. Once the front height gets taller so that the difference is less than 5%, the AH (or traction control) will sense a differential that is too small and activate, making tracking impossible.
(2) stickier tires change the car on the track as much as or more than any other single upgrade including tire size change.

godzilladude

I run Michelin PPS, 275/35/18, and 295/35/19, on CCW 18X10 and 19X11, everything stay under the car, no issues at all, and it does very nicely on the track.

But yeah, put some smaller semi-slicks on my stock rims, and it's go roundy round faster.

peter pan

Another here with CCWs on his base coupe and I run 275/35/18 front and 325/30/19 on the rear, oh the same as the GS/Z06 and we have the same power steering pump, I also run C6Z Sways and love my combo with the shocks also changed to Konis

BluV

I am running 275's on the front and 305's on the back. Base/Z51. Nitto Invo's for the street, but R-comps for regular monthly autocrossing and many HPDE days. 98k miles, daily driver, still on original steering pump.

2SlowinTO

5% of the overall height? so on a 27" O.D. tire you could be out by 1.35"??

I'm changing my tires, and want to clarify this as well.

The factory front to rear is 1.14” / 4.59% difference

What I want to put on 1.32” / 4.95% difference

I assume (hope) that is non-issue?

Racingswh

No issue. On my wifes car she runs Continental slicks with almost a 2.5" difference front 64.5 cm to rear 71 cm with no problems. She has done that for the past two seasons now.