I ran 15x7's 4.25 backspacing with a 255/60/15 tire no problem on my 70 Dart. When I switched to 15x8 4.5 backspacing the biggest tire I could fit was a 235/60/15 and it's really close the quarter
Yeah, ain't it amazing that with a wider wheel, you have to mount a narrower tire!
That's a direct function of most of the extra width being added on the fenderwell side.
I've got some 15x8 old style one piece mags that I can't really put any wide tire on, and same brand and wheel in a 15x7 that I can put two sizes bigger on.
