Iwas just about to order my IROC 18s from Performance Wheel Outlet and saw that they are no longer offering front and rear offsets, just the fronts. I phoned them up and they said "no problem, these will work"; are any of you running this setup?
I want to put these on my '88 IROC convertible, will I need to use the spacers that came with my factory 16" alloys?
Thanks for any help!

 

well the front offset is at a 0

the rear is at 18+ i believe....

so it all depends, obviously they won't work on the rear if they are made for the front if that's the case though without some work.

i'm sure someone else knows better.....to bad the search is down as mr.irocz has a nice set of 18's. he also goes into great detail on how hard they were to make work right though. which is also odd since they are a narrow rim.

o'well, wish i could help better....good luck. they will look great!

 

Offset depends on the width of the wheel. If the 18's are the same width as stock (18x8) then the offset will be the same as the stock wheels. If the width of the 18's are different from stock (wider or narrower), then you'll need to calculate the offset. For the most part, all the answers are already on this website ... Its just that people might have used a different diameter wheel. 17's are the most common, so you'll probably find the best examples searching for 17's. A 17x8 wheel in the front will have the same offset as a 16x8. And a 17x9.5 in the rear will have the same offset as a 18x9.5 ... see where this is going? By reading what other people did, you can find out what you need, 16's, 17's, or 18's. So to find the correct offset you dont really need to pay attention to what the diameter is, pay attention to the width. Since you're going with 18's I sidgest you research tire sizes and suspension setups that work with 18's. Having the correct offset will mean the wheel fits properly and clears all the brake parts and whatnot, but will not guarantee a perfect OEM spec setup. But yeah start with finding the correct offsets. There is a tech article on here that explains all of this as well. It dosnt give you all the answers out right, but after reading you'll understand how to calculate backspacing and offset. And since the search feature is down, I sidgest you start there. The stock offsets for a 16x8 are +0mm offset in the front and +16mm in the rear. If you got spacers stock, then I would continue to use them.

 

Thanks Crazy Hawaiian, but asyou probably already know the 'search engine" is down right now.
Guess I'll do the smart thing and wait till the board is repaired and do a little more research, BTW the wheels in question are 18 x 8" which are to replace my 16" IROCs Thanks

 

a 17x9.5 and a 18x9.5 can have completely different offsets....

the offset is determined by the maker.

the backspacing is typically the same in most cases when comparing rims, but even that varies from maker to maker.

 

If you have an 8" wide rim with a 0 offset front, I don't see why you can't use a 0 offset rim for the rear too. The rear rim would just stick out a little further than the front wheel.


If your car came with a spacer on the rear, then you should be able to run the same offset all around.