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Discussion Starter · #1 · (Edited)
On a 96 Impala SS would 20x8.5 5” BS, and 20x10 5.5” BS work, it’s lowered 2 inches?

On tires I plan on running:
Front 255/35/20
Rear 295/30/20
 

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Look up the specs on my wheels (should be the same as all Ridlers in that size).

 

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Yep. Body is shifted slightly to the left, it rubs the fender trim on dips on the RR. Took off the trim, took the sharp part down flat, and hit it all with a flap wheel. No danger to tires. My old 18x10s were more tucked, 6" BS. No issues.

You might be fine, but you might have to body shift (or do the trim trick).
 

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Just trimmed the wheel trim. It's pretty obvious what needs smoothing once you get the tire off and feel/look up in there, there are a couple spots where the metal inner part is sharp.
 

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Discussion Starter · #7 ·
So the factory 96 impala SS wheel has a backspace of 5” correct, and if I put a 20x10 w/ a 5.5” backspacing I’m only pushing the wheel .5” outward towards the quarter panel correct?
 

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It is easier to measure the offset instead of backspace, and compare it to the other wheel offset. The stock wheels have a 6 mm offset. If your wheels are the same, they should fit. You can play with the offset a little, but when you are trying to squeeze the maximum tire under the fender, sticking with the OEM offset will keep the centerline of the wheel/tire at the same place under the fender. This is important, especially on the front, where the wheels change their orientation when turning, and if they have the wrong offset, they will travel an arc that can cause interference, as well as putting pressure on the steering linkage that it was not designed for.
 

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Fronts are 20x8.5 5” BS 255/35/20 6mm offset
Rears are 20x10 5.5” BS 295/30/20 0mm offset


Car is lowered 2”
The fronts should fit fine, the rears may put the tire really close at the outside.
 

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Discussion Starter · #11 ·
Hey Jayoldschool, how much room did you have on the driver side wheel well, could you clear both wheels if you would of centered the body?
 

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Yes, it will easily clear both if/when I shift the body. I'll take you pics tomorrow. The unofficial measurement is "full four fingers on the left side, just the tip on the right side"...
 

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I won't, I worked on the car all day, and will be back at the shop tomorrow.
 

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Here we go! I really need to do the body shift, lol. Looks like my estimate was about perfect.

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Discussion Starter · #18 · (Edited)
Foreal Lol 😂 if you ever do the body shift mod, please be sure to document it if you will please, I searched on the forum for it, and wasn’t able to look at pictures, I’m assuming do to the info crash, I to would like to do the body shift mod.

Thanks Jayoldschool.
 

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It's largely a myth. Can body be moved a little? Sure ,likely 1/4" at most. GM did not install the body wrong. The drivetrain does not go down the exact center of the car ,but still has to be "square". Easier to install longer wheel studs ,and using different thickness spacers to make the relationship of tire/wheel to the wheel opening equal right to left. Mine is to 1/32" using this method.
 

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Most of the cars have the body offset to one side about 1/4 inch. The rear axle should be centered on the frame, and square with the frame rails (or you will be crabbing while driving), but the bodies were installed cooked. For the best performance you want the rear tires to run in the same track as the fronts. Putting a shim on one side does not correct the problem. The body can be shifted by loosening all of the body to frame bolts, and prying it to the desired side. If you can support the body a little, it takes the weight off of the contact points making it easier to move. You may have to move the front and rear bumper supports to keep the bumpers properly aligned with the covers. If you do this correctly, you will have the same space on both sides for maximium tire clearance. If you use a spacer, you will limit your tire clearance on one side.
 
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