back spacing on 17x8 wheels

[Pro-Touring79Cutlass]

any g-body guys ,what back spacing will i need to run 17x8s on all 4 corners on my 79 cutlass 2door ,its been lowerd 2inches in the front and 1.5 inches in the rear im looking at some 17x8 corvette ralleys from summit racing and they have a set of 17x8s with 4.5 iches of backspacing

[DriverzInc]

It'll work, although I personally like to see a little more back space, but I imagine you are just going to run a 245/45/17?

[mc84_zz4]

If you run 245s on the 8" wheel, the 4.5" would be perfect for the front, on the rear it should work fine as well, even up to a 255, depending on if you like the staggered look, but it would be barely noticeable.
You may have a bit of tire rub at full lock on the lower A-arm, rear side, I just smoothed mine down where they contacted, but it never marked the tire. After many miles, a front-end rebuild eliminated the problem.

On the Monte, the 4.5" bs put the outer edge of the tire just inside the fenderwell bolts, allowing to run 1" lower than a 4" bs would.
A 5" bs is the most you can run on the rear, assuming your tires also line-up pretty vertical with the wheel lips, an oversized tire on 5" bs in the rear would be pushing it, almost guaranteed wheel rub on the inner fender or frame.
Here are 2 pics showing a non-scientific method of measuring the available backspace, which actually is a 'hair' over 5".
HTH

[Pro-Touring79Cutlass]

yea im planing on running 245-45-17 on all around,so i can roatate the wheels to get more milage out of my tires and i like the look of ralleys on my car