Rob said:
4th gen F-Body wheels fit fine. The bolt pattern is .65mm difference. SLP races with Firebird wheels. Many have used them for everyday wheels also. I've seen pictures of WS6 wheels and they fit fine.
How thick is a human hair? The diiference of .325mm from lug to lug is probably the thickness of the paint on the wheels.
I spoke to the importer of ROH wheels from Oz. He told me to put my Z28 rims on the GTO and not to worry. They were 16" with snows, I sold them and got 17" BMW rims with snows for an additional $100. The hub on the BMW wheels is a bit bigger than the GM hub, so my rims are held on by lugs alone.
The more I think about it, the more I think the pattern is the same, just different labels. They arent going to say 4.72" or whatever, or say 120.63mm.
I think it is just rounding. I also think a steel lug not will "mold" the receptacle in the aluminum rim with just a little torque, especially if the wheel is tight on the hub.