I've got 265s on my '63 fleetside with room to spare. You can go as wide as you want without cutting the frame.. it's the fenders that would have to expanded.... offset rims.

Attitude - The difference between an adventure and an ordeal!
Deja Moo - The feeling you've heard this bull**** before!
'63 Chev Fleetside Longbox 'Rusto-rod' 'Big Red'
'69 or'70 or ? Mantaray DuneBuggy