The 15 x 7 Rally was only made in 5 lug, never a 6. All OEM 6 lug Truck Rally wheels are 15 x 8, and originally were used with the 10.00-15 tire option. They were used later with the 31x10.50x15 radial tire option, and some did get used with 235/75/15s, though that is pushing it a little bit with that size. I've mounted everything from the 235/75/15 all the way up to a 33x12.50.15 on them, but either a 30x9.50x15 (which is what I have on my truck) or 31x10.50x15 in a floatation size works best. You could also use a 255/70/15, 265/75/15, or a 275/60/15 on those wheels, as they are approximately within the proper width to fit the wheel correctly.
