Hi guys, im new on this forum, ive got an 86 IROC-Z with a 305tpi and a 95 formula with a 6spd and ttops. I recently purchased a pair of 17 x 9 inch SS wheels with the 50mm offset ( off of a 98 SS)out of the paper because the price was right. Well when i got them home, they'll only fit on the front of my formula, but not on the back. Can anyone tell me why, i know my iroc has front and rear wheels, is this the case for my formula???

 

Not the same problem. Your IROC requires different "offset" on the front and back wheels because the "width" of the front and rear suspensions are different.

That is not the case with the 4th Gens... you need the same offset wheels on the front and the back. The problem you are having with "fit" I''m assuming, is that the rear wheels will not fit over the raised hub portion of the rear axle. This is a very common problem.

Up to late 96/early 97 the hubs used on the rears of the 4th Gens were about 0.03" larger than the hubs used in the front. In late 96, or early 97, they corrected the problem, and made the rear hubs the same size as the smaller fronts. As a result, if you try to put "late" wheels on an "early" 4th Gen, the inside diameter of the opening in the wheel is too small for the hub.

All you need to do is lightly sand the inside diameter of the hole in the wheel until it fits comfortably over the hub. If you ever plan to "rotate" the wheels/tires, you need to sand the front wheels as well. This will not cause any problems... the wheels are centered by the conical lugs, not by the hubs.

 

hey thanks, its nice to have someone answer that question for me. I was lookin at it, and i was wondering, what deal was.Yes, indeed i was talking about the fit over the hub. Ive got another question, i also have a 17 x 9.5 with 56mm offset( would this be a corvette wheel?, its got a gsc 285 40 17 on it, corvette OE tire i think)inch wheel that was given to me, also a SS /zr1 style wheel, that wouldnt fit over the hub either, just sand it off a little bit again? the 9 inchers i got off the SS say GM on them, this 9.5 inch wheel i have, has a different lettering on it, but its the same lettering stamped in it, as on my factory 16 x 8 inch formula wheels. any idea what this wheel could be from??

by the way (injuneer) im in my third year of Mechanical Engineering and my formula is green with a t56 and ttops...