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Wheels and TiresNeed help with wheels or tires? Got fitment issues? Have questions about tire performance and handling? Ask all of those questions here!
Hey guys! I just picked up a 1986 trans am and I’m planning on gradually doing a pro touring build. I found a used set of GS1R wheels staggered with 18x10.5 fronts and 18x11 rear with a backspace of -20. I just ordered Koni yellows for all four corners and Eibach sport lines. Is there a chance I could make these wheels fit or is it too much effort?
Both the front and back wheels are not what we consider to be direct fit. By that I mean you'll probably have to do some work to make 'em fit without rubbing. How much kinda varies. As a rule, I think 9" to 9.5" up front with a 275 tire pretty much fits for everyone with just a smidge of rubbing in some cases. Nothing that can't be fixed with a thin spacer, if it's needed at all. Out back is about the same. Some guys are going wider with no problems, other's are needing to do a little bit of banging!!!! Keep in mind that the wider you go up front, the more "dialed in" the car needs to be to see the benefits. Wider tires can also tend to be frustrating on a daily/regular driver as they want to follow grooves in the road a bit more than stock.
I'd say pass, but you CAN make it work if you really want to. -Great looking car btw.
You know I didn't look close enough, but you're right. Just assumed +20 as I don't recall the last time I've seen a negative offset, but yeah your're right......that'd be problematic.
To fit 18x10.5 or 18x11 on a 3rd gen, you need 6in backspacing front, 6.5 or 6.4in rear.
you will need to cut and hammer your car as well.
Assuming the offset on those wheels are +20
that's about 6.5in of back spacing.
So you'd have to run a 1/2in spacer in the frontAnd a 1/4 spacer in the rear.(maybe 5/8 front 3/8 rear depending on the car)
that's actually what I do to fit 18x11s on my 92, that way I can rotate tires front and rear.
VERY important with our solid axles wearing out tires unevenly.
I have 3 vidoes covering the mods on my channel.
Hey guys! I just picked up a 1986 trans am and I’m planning on gradually doing a pro touring build. I found a used set of GS1R wheels staggered with 18x10.5 fronts and 18x11 rear with a backspace of -20. I just ordered Koni yellows for all four corners and Eibach sport lines. Is there a chance I could make these wheels fit or is it too much effort?
The easy answer to this question is call Forgeline and talk to them. They have wheel specs on file from both of my cars in 18x10.5 and the DSE-Z running 18x11 as well as several vehicles. They'll have some questions for you about your brake setup to make sure the arch of the wheel spokes will clear but they can set up wheels for you. There are more measurements required to properly spec these than just backspacing.
