dork

I've got my eye on an ad for a set of wheels; the seller claims they came from a c5 coupe.

The OEM offsets are 54mm (front) and 58mm (rear). The wheels I'm considering are 70mm front and rear. How would they change handling on a z06?

Would 17x11 wheels fit over the c5 z06 rear brake? (I don't have the car with me to swap the front wheel to the rear.)

Thanks very much, Guys.

c4cruiser

I would ask for pics of these 70mm offset wheels that were on a C5. Brake caliper clearance could be a big difference too. You're looking at a difference of 16mm for the fronts and 12mm for the rear.

Also, what is the wheel stud measurement for these wheels? It will need to be 5x120.65 to fit correctly.

Might be worth passing on these.

dork

Thanks, Gents!

The fronts are 17x10, the rears 17x11. The stud measurements are claimed to be 5x120.65. The weights are comparable to Speedline numbers-- 19.1 and 19.4 lb.--of course, the weight "gain" will be lost in the rear by the added weight of the bigger tire.

I posed the question because I'm leery of moving away from OEM standards. I've never ever substituted wheels with a different offset for OEM. The seller says he doesn't have pics of the wheels mounted on the car. That makes it feel like a real pig in a poke... the ad's been up for so long, I got the wonderment bug.

Thanks again!

Bill Dearborn

Sounds like the wheels may be CCW Classics. Those sizes were approved in the early days of C5 Competition in SCCA T1 class. A lot of people ran the 315/35/17 Kumho V710 on those wheels. The 10 inch front was a little narrow for that tire but it worked with the same tire mounted on the rear 17x11 wheel and they won races running that combo.


They could also run those the OEM C4 A Mold Grand Sport wheels 17x9.5 with a 56 mm offset in the front and 17x11 in the rear. These were the same wheels as used on the C4 ZR1 but the rear 17x11 used a 50mm offset rather than the 38mm for the rear ZR1 wheel. They used a 275/40/17 front tire which had the same tire diameter as the 315s. 25.3 inches.

If you can find some C4 Grand Sport wheels with the Grand Sport offset you can run 17x11 front and rear with 315/35/17 tires. I ran that setup for about 3 years on my 03Z. I ran the standard C4 setup for 3 years on my 97 and then a couple of years on the 03Z.

The 17x11 GS wheels will stick out a little from the side of the car while the CCW Classics fit inside the body. The 17x11 GS wheels will rub the inside of the barrel against the lower control arm in tight turns in the garage/paddock. I stripped a number of wheel weights off the wheel doing that until I started using glue on weights that weren't placed at the edge of the barrel.

It isn't the wheels that change the handling so much as it is the tires the wheels let you mount. After used Kumho DOT R tires dried up I switched to stock 18x10.5 Z06 wheels all the way around and never could get the handling I got with the previous setup. With the 315s on all 4 corners the car was a handling monster. Throw it into a corner and drive out. Higher entry speed, higher speed through the corner and higher exit speeds.

If the wheels you are looking at are the Classics then 70mm offset would play well. The 50 mm offset of my C4 GS wheels would leave them sticking out of the fenders a little. The added 20 mm would bring the outside of the wheel inside the fender lip. 20 mm is a little less than an inch (25.4 mm). Here are a couple of pictures showing the GS offset 17x11 wheels on my C5Z:








Hope this info helps.

Bill

dork

Thanks very much for all ya'lls responses. I think I'll wait for something closer to OEM. I wasn't planning to track the car often so I think the square 17s would be too extreme for my needs especially now that I understand their application better. Maybe even square 18s wouldn't be a good idea for the street but I think at least tire availability would be less problematic for daily driving 18s than 17s.

Thanks very much again!