Grand Sport and ZR1 wheel question....offset and backspacing


I am most likely going to be purchasing a set of "Original black ZR1s" from a guy. My question is this: If they are real GM wheels and they are black, they will be 50mm offset, correct? (The only wheel that came this way was a GS wheel, correct?) How can I determine if they are the correct offset that I need? Will there be a part number, or a "50mm" anywhere on them? I guess I could measure the backspacing, I think 50mm is a 8" backspacing, and a 56mm offset is a 7.625" backspacing, sound right? Thanks, Shawn

 

The real GS 17x11 wheels are 50mm offset. That makes them a shade under 8" backspace... maybe 7.93".

Not sure what offset they used on the front of GS coupes. I don't think the GS was any different than any other C4 in the front. Only the back had the wider wheels with the little eyebrow added to the outer edge of the fender lip. If you get a 56mm offset 17x9.5, the backspace will be a little under 7.5".... about 7.41.

The real GM wheels will have a "GM" emblem on the front of the wheel.