Tire clearance

Another wheel tire combo I tried on my Dart were the rear wheels and tires off my 2012 Challenger R/T Classic with the 20x8 inch wide Cragar SS looking wheels with 275/40/20 tires.
Those wheels have 5.5 inches of backspacing and the tire are 10.5 inches of section width. Other than I thought the car looked a little odd with the 20 inch wheels, that combo fit nice and didn't rub at all.
I found out that 15x7 weld wheels not only have a 4.5 backspace but have a +13mm offset