I've got stock tires so can't offer alternatives, but I can assure you that changing air pressure (especially in the front tire) will make a big difference. Especially don't overinflate (i.e. don't go above 18 psi) for dirt riding, and you probably will be much more comfortable and surefooted at 15 or 13 depending on the rock size, amount of washboard, and speed. The one time someone aired my tires to a pressure above the recommended psi, I thought I was riding a 2 x 6. I check my tires every time I ride, because too soft is not fun either. Tom