If I were not planning to go wider than 12.50" tires and I planned on airing down to low pressures, then I would choose the 15x8s. However, I would be willing to keep a couple of extra pounds of air pressure in the tires while off-road if it saved me enough money (I.e., a cheap set of 15x10s might not be too bad compared to an expensive set of 15x8s). 15x8 wheels have less exposure to rock rash opportunities than 15x10 wheels.