Rear tire size on a 75 Dart
Ok, so in the back the 15x7" with a 4" backspace would be fine. The BBP 7.25/8.25 is actually narrower than the A-body 8 3/4 so you don't need all that much backspacing in the rear. But in the front a 15x7" with 4" of backspace would be pushing your luck even for a 225/60/15. To put it into perspective, the 225's on that rim would stick out 5mm
further than the 275/35/18's I run on the front of my car. Doable if the ride height is high enough, but yeah, right on the edge. To be at my current ride height with the 275's I rolled my fenders.