Hey Guys. We just bought a 2000 Z28 convertible. A prior owner put 20in. wheels with low profile tires on it. Although they look great, the tires rub when you drive over a bump or dip in the road. It's really bad when anyone is in the back seat. I believe the rear shocks have not ever been changed. So we intend to replace them. Although it's still probably going to rub if we just put stock shocks back on. What would you recommend we do to correct the problem? I'd appreciate any advice. Thanks

 

Sell 20" rims, buy smaller/lighter rims, use left over money (if any) for mods

Btw congrats on the car. Post some pics!

 

The suspension on the 4th Gen was not setup for that large of a wheel/tire combo. To keep from rubbing the tire you would need to stiffen the rear suspension to the point where the ride quality would be horrible. Air bags in the rear coil springs would likely get you there.

 

First, you need to identify the width and offset of the wheels. If the offset isn't correct, the inside edge of the tire can rub on the inner fenders, or the outside edge of the tires can scrape on the fender lip.

Then there's the issue of tire diameter. You have to stay as close as possible to the stock tire diameter, or it screws up the speedometer, and usually ends up with a tire that is too tall, and rubs.

Finally, there is the issue of whether the rear of the body is accurately centered over the rear axle. If not, an adjustable panhard rod may be required to recenter the body correctly over the rear axle.

Has the car been lowered?

What part of the tire(s) rubs on what part of the chassis?

What size tires are you running?

What is the width and offset of the wheels?

As noted above, even after you solve all these dimensional problems, a 20" wheel/tire combo will not provide the compliance required for a solid rear axle, as used on the 4th Gen F-Bodys. It will never handle right, the paper thin tire sidewalls will provide an extremely harsh ride, and leave the wheels susceptible to damage from potholes.

 

I ran into the same problem on my rear fenders so I bought some lift shackles and
shock extensions it raised the rear about 1 .5 inches. After doing this it would be wise
to check your pinion angle. They took about 30 min to install.

 

First, we need to know were the tire/s rub, at the fender lip/s, or inner wheel well/s and is this the left/right side, or both?

 

Don't worry about it. He never came back to the site after his first post above. Looks like we just wasted out time.

 

I would like to know this answer too. I was planning on running some 20' that came off my C5 before I sold it. The Z28 is lowered 1 1/4 inches, front tires are 245/35/20 rears are 295/25/20. Can I get these to work some how?

 

You have to answer the questions I asked about width, offset, etc. in post #4, above. Without knowing the width and offset of the wheels, there is no way anyone can answer your question.

With the tire sizes you quoted above, the front tires are going to be about 1" larger in diameter than the rear wheels. Might look a bit "odd". You could equalize the tire diameters by using a 245/30-20 in the front.

 

You are correct, the front tire is 245/30/20

Front is 20x8.5 42 offset

Rear is 20x10 42 offset.

Thx for the advise.

 

The front should be fine. It's sitting toward the outside edge of the fender, but it's only about 1/10th of an inch further out than the stock 9.0" 50 mm wheels used on the WS6 and SS coupes.

The back is going to be close to the fender lip. Lots of clearance on the back side though. With a 295 tire on it, it shouldn't require rolling the fender lip.

I just can't understand the attraction of 20" wheels on a solid axle vehicle. The suspension just can't cope with the paper thin sidewalls, like the IRS in your Corvette could.

 

Thank you very much for your answer, I too agree the 20'" might look wrong. I am building a Factory Five GTM and I got the wheels for that car. When I put them on the GTM the were way too big so they ended up on the Vette for about 1000 miles. The tires are high-end, the wheels although nice are from a company no longer in business.....so to sell them I would need to near give them away. I have about $2500.00 in this package. So since they are sitting in the garage I figured "why not". If they look wrong then I will need to go a different route. This car will see very light use, maybe a couple thousand miles per year. The goal is a weekend car that I can show and when wanted, switch to drag wheels/tires and shoot for a low 11sec pass. Shooting for 450whp at the wheels.

I was able to buy this car back 16 years after I sold it so this time around I can afford the things I could not afford before. Still up in the air if I am going Nitrous or STS???? If I could figure how to post a pic I would post a few pics of the wheel on the Corvette.

 

And if you were wondering why I just did not try them on the car, it is because the Camaro is at one buddys shop getting the engine put in and the wheels are at another shop about an hour and a half in the other direction.