jpasterjak

Okay, I'm getting ready to order tires and just wanted to see if anyone had had any trouble or has any recommendations regarding my proposed setup. Since I have to retain the stock 8.5" front and 9.5" rear wheels, my choices ar somewhat limited for stickies. Right now I'm looking at Kumho V700s, 275/40/17 on the front and 305/30/18 in the rear. I'm confident the fronts will fit on the 8.5 no sweat, but I'm a little worried about the 305s stretching onto the 9.5s in the rear. Anyone have any experience.

Also, the 305's are about an inch and a quarter less in diameter than the stock setup in the rear. While I like the gearing advantages, I've heard horror stories of ABS and traction control computers freaking out. True, or urban legend?

And if I'm waaay off base here, what is a useable setup for the stock C5 wheels?

thanks.

J.G. Pasterjak
Production Director
Grassroots Motorsports
Classic Motorsports

RAFTRACER

Tire size difference will play hell with the traction control/active handling and ABS. More the traction control than anything, but will defineatly effect the others.

The 305/30/18 Kumho Ecsta V700 will be a major PITA on the 9.5" rear wheel, but can be done.......Leave the tires set out for a long time in your hot Florida sun to make the tires more pliable and that will help emmensly, but you will still be using exclamatories..........

I havent researched lately, but the stock C5 and C6's (non-z06) stock sized wheels are not easy to find DOT R tires for , the tire manufacturers never targeted those sizes.

Good Luck

Solofast

I'm seeing the Solsti (I think that's how you say the plural for Solstice) do some amazing things on the Hoosier R6's and they weigh almost as much as a Vette and have a width limited 18 inch rim.

They are using 285/30/18's, but that is a bit small in diameter for your rear tire, but the Tire Rack has them in 295/30/18, which would be almost the same diameter as what you can get on the front. Not that bad on the back, and it is more rubber than all the C4's use. If you coupled that with a the right front tire (I'm thinking 275/40/17) (yes it's a squeeze, but if the Solstice can run a 285 on 8.5 inch rim I think you can get away with a 275/40 on yours, they recommend it down to 9 inchs, and you are only a half inch below that) you shouldn't be too far off in diameter, the backs would be within .1 inches of the fronts. I see a lol of people running a "square" setup (same tires front and back) without problems, so that's where I would start..

That's gonna be in a different time zone when compared to V700's, the Hoosiers are a lot faster and I don't think you would give up much

UstaB-GS549

My personal opinion is that those stories are urban legend. I suspect that those having ABS/TC/AHC issues, are caused by other electrical gremlins. See Bill Curlee sticky in C5 Tech regarding loose & corroded connectors.

My current tires are GY 315/35-17 GS-CS fronts on 9.5" rims with same size V710 on rear 17 x 11" rims. In theory my front and rear tires are the same diameter. Squeezing the front 315 on a 9.5" rim may actually make front tires larger in diameter. (I'm not suggesting that this tire combo is optimum... I'm just cheap & these were available. )

The stock Z06 has larger diameter rears than fronts.

My last set of tires were 275/40-17 & 315/35-17 which are same O.D. I drove on this combination from Chicago to Elkhart Lake (about 140 miles each way) and ran Road America for 2 days without anything strange happening.

XPC5R

JG,

I have 275/17 and 305/18 Hoosier rains mounted on my standard C5 wagon wheels. They look only slightly squeezed, even on the rear. Other than mounting challenges with Kumhos, they should work fine.

Stan

jpasterjak

Sounds like I'm in the ballpark then. Thanks for the backup.

J.G. Pasterjak
Production Director
Grassroots Motorsports
Classic Motorsports

Kschwamy

I have a set of Kuhmo 710's on stock C5 wagon wheels with 275's on the front and 315's on the back. The fronts went on with no problem. The rears were a totally different story but had no problems and ran them for 150 auto-x runs. We run with the traction control off so can't answer that question but if Danny says there will be issues I would have to believe he has either seen them or experienced them. Have now gone to the 275 front and 295 rear Hoosier A-6 setup and am happy with that.

TedDBere

I run Hoosier A6 275/40/17's and 285/30/18s on the stock rims. You must turn the traction control off or else the computer thinks the rear tires are spinning and reduces power.

I don't go wider on the rears because I need the gearing to keep up with the Elise's and Z06s in SS. The 295s are taller and no wider than the 285s. 305s and 315s are just too tall for the MN6 second gear to be competitive.

710s and A6s are the only competitive R comps in autox. Any other tire is just for fun IMHO.

Good luck.

jpasterjak

I think we're going to end up starting with the 275fr and 305rr setup. The 305s are over 1.5 inches shorter than the stock tires, so that should be quite a reduction in gearing. Not as much as the 285s, obviously, but a step in the right direction.

The reason we're going with 700s and not 710s is editorial and not so much competitively based. We need to be able to drive to local events on the tires, and 710s or A6s are just too slick to be really safe if weather comes up. The car's not going to be competitive in SS against the Z06s anyway. When we loked for some "drive to the event" stickies, the only thing that really looked like it might work were the 700s or Nitto NT01s. Nitto had already committed to supporting another project, so we didn't want to overwhelm them with questions. Also, the 700 seems to have gotten lost in the shuffle since the 710 came out. It'll be nice to revisit what is really an excellent tire and see if it meets our needs while also being competitve against the clock.

J.G. Pasterjak
Production Director
Grassroots Motorsports
Classic Motorsports

Bill Dearborn

As long as you keep the rear tire size the same diameter or larger than the fronts you will be OK. If it is smaller then traction control will have a fit. The 275/40 fronts should have a 25.3 diameter. If you are going to run NCCC events you can move to Group IIH by going with GS wheels and running 275 front and 315 rears or 315s all the way around.

A friend tried the ESCTA Kumho when they came out a couple of years ago and found he had to run the rear tires on the front to avoid TC problems on the way to events.

I have been running the 275/315 (25.3 front and rear)combo for 6 years with no problems.

Hoosier and Goodyear make R compound tires that fit on your stock size wheels. Not sure how long the GYs have been on the market but I used the Hoosiers on my 97 starting in 98 and ran them through 99. I got tired of them because I had to keep replacing the front tires due to cording the outside edge.

Bill

mountainbiker2

1. As long as the rear diameter is a little bigger then the front you will be fine.
2. My buddy use to run 275/40/17 on stock 8.5 rims. 315/35/18 on stock C5 9.5 rims. No problems at all.
3. I drive 60 miles on my 710's each way to the event. I get about 140 Auto X runs on them.
4. Have driven in the rain, hard at sometimes with V710's at 55 mph. No problem. Even some standing water on the freeway. Just take it easy is the key.

Steve

LehmanZ06

V710 should be fine in rain....

I remember when Hurricane Wilma blew threw, and I had to drive to Key West----no problem as the wind kinda cleared the road of rain.

Only problem I had was between gusts as the wind did not move the giant 3" puddles----car went airborne.......

thrown up to the clouds, but since I didn't have a oxygen mask with me I passed out and the next thing I knew I was on top of a oil platform in the middle of the Gulf of Mexico ! (boy was that a bitch getting the car off of that thing).

Rain V710's on a public road they go together Like peanut butter and jelly..............

WHAT ARE YOU CRAZY !