OK I need to know what offset I can put on the 97 z28 convertible. I know it's different from the hardtops.

Also are there any advantages to having a certain offset?

 

The "offset" determines how far into or out of the wheel well the tire/wheel sits. Too much offset and the inside of the tire hits the inner fender liner. Too little offset, and the wheel/tire is outside the fender.

To my knowledge, the coupes and convertible offsets are the same. I base this on direct comparison of my 1994 Formula coupe and a friend's 97 SS convertible.... same size ZR1/Grand Sport wheels, and they fit the same.

In general, required offset depends on wheel width. A 9.5" wide wheel will work with ahywhere from a 45mm to a 56mm offset. The 45mm is going to be very near the edge of the fender in the front. The 56mm will be very close to the steering knuckle.

In the back, if you were to go to an 11" wide wheel, the 50mm offset works best..... minimum hammering on the inner fenders, and the tire stays JUST under the top edge of the fender. Any more offset and it won't work... it will be hard into the inner fender liner, any less offset and the tire starts to protrude from the fender.