Correct back spacing

[cuda guy]

Hey all

We installed a 68 b body rear end in our 1971 Demon

Our question is what would be the correct back spacing for this combo and can I use my rims from our 07 Magnum RT on this app

Thanks all

 

[72bluNblu]

Stock A body spring locations? Quarters rolled or trimmed?

What size tires are you wanting to run?

That 2007 Magnum R/T has a 5x115mm bolt pattern, it's not the same as the 5x4.5" pattern on that B-body rear axle (5x114.3).

 

[cuda guy]

Stock A body spring locations? Quarters rolled or trimmed?

What size tires are you wanting to run?

That 2007 Magnum R/T has a 5x115mm bolt pattern, it's not the same as the 5x4.5" pattern on that B-body rear axle (5x114.3).

All stock on the Demon
I know that the rear end is wider so may some nice 17 x 8 with 6 " back spacing

 

[72bluNblu]

All stock on the Demon
I know that the rear end is wider so may some nice 17 x 8 with 6 " back spacing

That would work perfect actually. 17x8's with ~6" of backspace (+38 offset) a set of 255/45/17's and you should have plenty of clearance to the quarters and the springs. With that set up you have about a 1/4" either way to mess with, so anything from ~5.75" to ~6.25" should work for the backspacing. Maxed out would be a set of 17x9's with ~6.5" of backspace (still a +38 offset) with 275/40/17's. The 275's will be tight on a stock car though, so if your car sits low it will depend on body tolerances.

I run a set of 295/35/18's on my Duster with a 68-70 B body 8 3/4, on 18x10's with a +38 offset (7" backspace). But I have a 1/2" spring offset and cut about a 1/2" off the quarter lips to clear those. That's why the offset measurement is so handy, it keeps the wheel centered even as the wheel widths change. Because I have an extra 1/2" on either side you just use the +38 offset number, run a narrower rim and tire to get back the 1/2" I have that you don't, and go from there.