Hey there 72bluNblu- thanks for the feedback.
So...you say:"A 15x8 with 4.5" backspace should work too"
Does this mean I can actually fit a 8"wide wheel(in the rear)- just as long as my backspace is 4.5" and that I go no larger in tire size than a 235 or 245?
If so- then that tells me I should have no issue fitting a 15x7 wheel with 4.5" backspace-right?
A 15x7 with 4.5" of backspace should fit just fine. That rim would have the same offset as a 15x8 with 5" of backspace, which should also fit just fine on an car with an A-body 8 3/4, especially with BBP axles.
On my '71 with an A-body 8 3/4 and BBP axles I have 6" from the wheel mounting location to the springs, and 5" from the wheel mount to the quarter lip. For a rim that works out to an offset of ~13mm to center the wheel, which is exactly a 15x7 with 4.5" of backspace or a 15x8" with 5". Now, you can go with a little more offset/backspace than that, because you need a little more room to the quarters than you do to the springs. No more than a 1/4" of additional backspace though, so I'd say 15x7 with 4.75" of backspace or 15x8 with 5.25" would be a about the most you wanted to go, unless you don't mind using a small spacer to make up any difference beyond that.
8" wheel in the rear will not work w/a stock rear unless you relocate or offset the springs and play w/the b/s.
A 15x8 will fit in the back. Wanna know how I know? Because I mounted a 17x9" rim on my Dart. The key is tire choice and the backspacing on the wheel. A 15x7" is more than wide enough to run a 245/60/15, which is probably the biggest tire you're going to fit in the back without trimming or offsetting the springs. I know that on my '71, I have 11" from the quarter lip to the inner wheel tub. That means if I set the backspace up perfectly, I should be able to run a tire with a section width just over 10". A 245/60/15 has a section width of 9.8", so at least on my car that will work with the right backspace. And the rim can be any size that the tire will safely fit on, the tire is going to be the widest part unless you go all "tuner" and stretch the tire on a rim that's too big.
Just put 15x7 with 4.5 backspace on our 70 dart with 225/60-15 tires. Fit nice but if I did it again I'd go 4.75 backspace. Stock Chrysler 4.25 backspace just stick out too far for me.
That's the BBP axles. The combination of BBP axles and brakes adds about a 1/4" to 3/16" or so to the width of the wheel mounting location compared to the SBP. And those specs match right up with what I measured on my '71, so that makes sense.
