15x8 cragars what size rear tire

Just bolt them on w/o tires and then look at clearance. a 235 series tire is 9 1/4 inches wide, which would stick out another 5/8" from the rim. A 255 is 10" or 1" wider then the rim on each side. Any of those in a 60 series should be ok height wise, just look at the fender lip and the leaf spring.