255-60's will fit on 15x7's on a 70 Swinger

If they will keep traction and not break loose really easily I'm gonna run 235 75 15. I just happened to have a new set in my building so I'm gonna try them out if they work I will stick with that size. If not I guess I will be doing a spring relocation

A 75 series is a crapload of sidewall.