What's the widest wheel and offset that will fit on 68 cuda

DesertRat said
275-60R-15 on 8" LBP wheels and 4.250" BS. That is mounted on a 73 A-body 8 1/4 rear end.
No spacers and no clearance issues.

That makes sense to me.

LBP 8 1/4 is tiny bit wider that SBP 8 3/4. And the 4.25 backspace pushes the tire outward a little too. Most 15x8 rims are 4.50" backspace