Need some help picking tire sizes for a 4/6 drop

[StorminNorman]

This is my '81 . "4/6" drop - flipped rear and belltech 3" drop spindles with one coil cut on stock springs.
The 18" wheels and 255/55R18 tires came with the truck, Don't look too bad but the front does rub quite a bit. It hit the part of the inner fender where its lowest and bolts to the outer fender. I think these tires are about 29" tall.