I'm not sure about 86's, but w/ 87+ I think you can sqeeze 245's under there w/ the quad shocks. You get additional clearance by flipping them though. I'm gonna try to fit 275's under my GT on 15x10's; might have to beat and bang a little bit and flip the quads, but I've heard they'll fit. We'll see.
My set up in the rear is a little unusual. I replaced the stock rear in my '90 GT with the rear from a '95. This had the disc brakes and 3.27 gears I wanted. I am using the '94+ wheels in the rear. The wheels are 17x9 Cobras. The tires are 275/45. I did have to pull the lip of the rear fender up. However the fenders still look original. I am still running the quad shocks, and I have no clearance issues there at all. It is possible that if I used the fox-body wheels I would have been able to leave the fender lips alone?
Don't know if this will help with your application, but it shows how you can get creative.
Good Luck.
My set up in the rear is a little unusual. I replaced the stock rear in my '90 GT with the rear from a '95. This had the disc brakes and 3.27 gears I wanted. I am using the '94+ wheels in the rear. The wheels are 17x9 Cobras. The tires are 275/45. I did have to pull the lip of the rear fender up. However the fenders still look original. I am still running the quad shocks, and I have no clearance issues there at all. It is possible that if I used the fox-body wheels I would have been able to leave the fender lips alone?
Don't know if this will help with your application, but it shows how you can get creative.
Good Luck.
Since fox body wheels are obviously 4 lug, you couldn't use them at all. All you would have had to do would get a bigger offset and space it properly and it should fit unless you're getting big wheels. I think the SN95 rear makes the rotors stick out 1/2 inch on each side farther than stock.
nidy: I think the key here is gonna be your offset/backspacing(same thing). If you don't know what that is, it's the amount of space from the center part of the wheel to the back lip. If you don't understand, do a search in google or something and you'll find write-ups. Anyway, to fit my 15x10's, I had to go w/ 6.5" backspacing/offset. I haven't officially put them on yet, but a few on here have and say it fits w/ some beating/banging of the inner fender. You might end up having to roll your fenders a little bit or something if you don't have enough offset.