'85 Pontiac GP 17" wheel fitment?

[Shinobi68]

I have looked at quite a few threads and am not exactly sure what wheels provide the best fitment. The "Let me see your big 17" wheels" thread is not definitive on what wheel tire combo fits without rubbing. I may have seen one poster with a nice-looking car go with a 17x7 17x8 setup that seem to have no issues. I also seem to recall reading that the GP has less room than some of the other G Bodies.

I'm looking at G Body parts site and filter Pontiac. The wheels that come up (which I like) are the G Body Only Aluminum Super Stock II set of 4 17x8 4.5" back spacing. Are these the safe solution, or will the same wheels in a staggered 17x8 4.5" and 17x9 5" bs work? I would like to use wider tires in the rear with my LSx swap. I also like the GN wheels (Turbo style).

Thanks

 

[clean8485]

Several years ago, I purchased a staggered set of 17" aluminum rims from Year One. These are the rims that look like the '78-'81 Camaro steel 15" by 7", and the '71-'72 Chevelle SS 15" by 7" rims. The Year One rims have the same dimensions that you have quoted. The front rims are 17" by 8" with 4.5" BS, and the rear rims are 17" by 9" with 5" BS. I mounted 245/45 tires on the front rims, and 255/50 tires on the rear rims. The first car I ran this combination on, is a 1980 Malibu. I was using 7/32" thick spacers on the rear. The left rear tire had roughly 1/4"-3/8" clearance from the inner sidewall of the tire, to the frame rail and wheel tub. When I first installed the right rear tire, it appeared like I had about 1/8"-1/4" of clearance in the same areas. After driving the car for several months, I removed the rear wheels, and I found that the inner sidewall of the right rear tire had been just barely touching both the rear frame rail, just ahead of the rear axle, and the rear wheel tub in the same area. I transferred these wheels onto my 1984 Monte Carlo SS, using the same spacers on the rear. I have run this wheel & tire combination for several seasons now, with no issues with them contacting anywhere, although the clearance between the inner sidewalls of the rear tires, and the rear frame rails/wheel tubs is tight.
One thing you have to keep in mind, is that, on the '78-'88 A/G body cars, the rear axle housing is not always perfectly centered between the frame rails/wheel tubs on these cars. Some people claim that, because of factory build tolerances, that the body is not always perfectly centered on the frame, but I think that there are tolerance issues with the rear suspension on these cars as well. I have watched a video on the UMI website, that shows how to use their adjustable rear upper control arms, to adjust the position of the rear axle, relative to the frame, to compensate for this situation, but I haven't tried this myself.
As for rim sizing, if you're looking to be sure of adequate clearance on the rear, I would suggest that you try to go with a rear rim with no more than 4 3/4" BS. I'm only saying this going from my own personal experience, as I'm sure that there are others here, who have had different experiences in this regard.

 

[Ribbedroof]

I had 5" backspace 17x8 Eagles on a wagon, and the 245/45 tires rubbed the frame

Running 17x8 4.5" backspace with 245/45 all around on my avatar and couldn't be happier

 

[Shinobi68]

Several years ago, I purchased a staggered set of 17" aluminum rims from Year One. These are the rims that look like the '78-'81 Camaro steel 15" by 7", and the '71-'72 Chevelle SS 15" by 7" rims. The Year One rims have the same dimensions that you have quoted. The front rims are 17" by 8" with 4.5" BS, and the rear rims are 17" by 9" with 5" BS. I mounted 245/45 tires on the front rims, and 255/50 tires on the rear rims. The first car I ran this combination on, is a 1980 Malibu. I was using 7/32" thick spacers on the rear. The left rear tire had roughly 1/4"-3/8" clearance from the inner sidewall of the tire, to the frame rail and wheel tub. When I first installed the right rear tire, it appeared like I had about 1/8"-1/4" of clearance in the same areas. After driving the car for several months, I removed the rear wheels, and I found that the inner sidewall of the right rear tire had been just barely touching both the rear frame rail, just ahead of the rear axle, and the rear wheel tub in the same area. I transferred these wheels onto my 1984 Monte Carlo SS, using the same spacers on the rear. I have run this wheel & tire combination for several seasons now, with no issues with them contacting anywhere, although the clearance between the inner sidewalls of the rear tires, and the rear frame rails/wheel tubs is tight.
One thing you have to keep in mind, is that, on the '78-'88 A/G body cars, the rear axle housing is not always perfectly centered between the frame rails/wheel tubs on these cars. Some people claim that, because of factory build tolerances, that the body is not always perfectly centered on the frame, but I think that there are tolerance issues with the rear suspension on these cars as well. I have watched a video on the UMI website, that shows how to use their adjustable rear upper control arms, to adjust the position of the rear axle, relative to the frame, to compensate for this situation, but I haven't tried this myself.
As for rim sizing, if you're looking to be sure of adequate clearance on the rear, I would suggest that you try to go with a rear rim with no more than 4 3/4" BS. I'm only saying this going from my own personal experience, as I'm sure that there are others here, who have had different experiences in this regard.

Several years ago, I purchased a staggered set of 17" aluminum rims from Year One. These are the rims that look like the '78-'81 Camaro steel 15" by 7", and the '71-'72 Chevelle SS 15" by 7" rims. The Year One rims have the same dimensions that you have quoted. The front rims are 17" by 8" with 4.5" BS, and the rear rims are 17" by 9" with 5" BS. I mounted 245/45 tires on the front rims, and 255/50 tires on the rear rims. The first car I ran this combination on, is a 1980 Malibu. I was using 7/32" thick spacers on the rear. The left rear tire had roughly 1/4"-3/8" clearance from the inner sidewall of the tire, to the frame rail and wheel tub. When I first installed the right rear tire, it appeared like I had about 1/8"-1/4" of clearance in the same areas. After driving the car for several months, I removed the rear wheels, and I found that the inner sidewall of the right rear tire had been just barely touching both the rear frame rail, just ahead of the rear axle, and the rear wheel tub in the same area. I transferred these wheels onto my 1984 Monte Carlo SS, using the same spacers on the rear. I have run this wheel & tire combination for several seasons now, with no issues with them contacting anywhere, although the clearance between the inner sidewalls of the rear tires, and the rear frame rails/wheel tubs is tight.
One thing you have to keep in mind, is that, on the '78-'88 A/G body cars, the rear axle housing is not always perfectly centered between the frame rails/wheel tubs on these cars. Some people claim that, because of factory build tolerances, that the body is not always perfectly centered on the frame, but I think that there are tolerance issues with the rear suspension on these cars as well. I have watched a video on the UMI website, that shows how to use their adjustable rear upper control arms, to adjust the position of the rear axle, relative to the frame, to compensate for this situation, but I haven't tried this myself.
As for rim sizing, if you're looking to be sure of adequate clearance on the rear, I would suggest that you try to go with a rear rim with no more than 4 3/4" BS. I'm only saying this going from my own personal experience, as I'm sure that there are others here, who have had different experiences in this regard.

Appreciate the detailed response from your experience, those are from the Year One and GBody Parts sites. I really don't want to run spacers if I don't have to but am not opposed to them either.

I had 5" backspace 17x8 Eagles on a wagon, and the 245/45 tires rubbed the frame

Running 17x8 4.5" backspace with 245/45 all around on my avatar and couldn't be happier

This will most likely be the route I take. I'm mainly going to be using this car as a daily driver/grocery getter. I inherited it from my Grandfather when he passed away and the V6 was underwhelming and leaked a lot of oil. I was going to swap a 327cid w/350 Auto that I had, but then I came across a really low mileage LS1 with 4L60E out of a 2004 C5 Vette. I also replaced all of the stock suspension and rear end w/posi and 3.42:1 axle ratio. It's going to be a fun daily driver. It currently has 14" wheels on it and they have to go lol.