I just purchased a set of powdercoated white Zr1 wheels and tires for my '98 SS. They are 17"x9.5"(front) & 17"x11"(rear) and they include Joust spacers. I need to know what modifications will be needed to fit the wider 11" wheels on the rear of my car?

Thanks in advance
Jason

 

Are they TRUE ZR1 rear wheels with a 36mm offset or are they replica ZR1 wheels with the more common 50mm offset?

 

They have either a 50mm or 56mm offset, I'm not positive. They were originally purchased from GM.

 

If they were originally purchased from GM and have one of those offsets, I do believe it'll be 50mm and they were originally black. If not, then they aren't GM wheels. I'm pretty sure you could only get the 11" wide ZR1 "style" wheels in the 50mm offset in BLACK. The silver ones were true ZR1 wheels and have a 36mm offset.

If they are the 50mm offset then you may not need to do anything. Or, you might have to pound in the fender well a bit. Or, you might have to roll the fender lip. Or, you might have to buy an adjustable panhard bar to center the rear. Or, you might have to modify the bump stop bracket a little. You might need to do none of this, all of it, or a combination. It seems everyone has a different experience in this area.

What I recommend is just try them. If you have problems you'll know what you need to do based on your test fitting. The only thing that requires purchasing anything is an adjustable panhard bar and you should be able to measure right now to see how far off your rear end is. If significant, you'll probably need one.