[Singleton]

Here’s a 275/60-15 (M&H bias ply), on a Billet Specialties StreetLite wheel (15x8 w/5.5 backspace). Barely fits on front side as well as back side.
As B-man said, backspace is critical. Also critical is which rear axle that you’re using. I have the wider 66-72 rear, (1/2” wider per side), in my 64.
If you have the narrow 64-65 rear, you may need a 1/2” spacer to run a 5.5”backspace, (or try to find a 8” wheel with a 5” backspace.