I'm going to do some experimenting with my wife's 1971 R/T Challenger this summer.
I've been collecting parts for years.
I have a 1970 B body rear end that I'm going to install with Dr. Diff's offset hanger kit.
My wheels are custom made Torque Thrust 15x10 with 5 3/4" back spacing.
The tires are 325/50-15 BFG drag radials that are listed as 28" tall 13" total width with 11.75 tread width.
I hope to tinker with some 1/4" wheel spacers and see if it will fit.
I test fitted 28x12.50 ET streets under our other stock width 1971 R/T Challenger on 15x8" rims with 4 1/2" back spacing with no problems...see pic below.
I plan to re-test fitment of the ET Streets now that the car is sitting lower.
In the bottom pic I'm using a 15x8 rear wheel with 275/60-15 street radial tires and have plenty of room.
The Dana is stock E-body width.