Want to buy a set of 17 x 8.5 and 18 x 9.5 rims from a C5 Vette. Anyone put these on a f-body??? Will they fit, I was told the 18 won't clear in the rear?

 

Yep, they'll fit . Don't get carried away with super wide tires in the back, or you "may" end up with clearance issues, requiring the BFH mod (big _ hammer). I've got 2 buddies with C5 rims on their LT1 F-bodies. One of them had problems getting the back wheels over the hub, and apparently it's a problem with earlier LT1's ..... all you "may" need to do is sand, or lightly grind out a small amount of material from the inside surface of the rim where it fits over the hub IF that poses a problem for you. Again, it's only in SOME cases, not all. But the rims should fit without needing any spacers.

 

The 18x9.5" OEM rear wheels will have limited POTENTIAL problems, because the 61mm backspace gives them a 7.60" backspace.

The issue of late model wheels not fitting over the rear hubs of 96 and earlier 4th Gens is also covered in the FAQ.