I put all new tires on mine. I went with a 23 inch Kenda Claw in the front, for just a little more clearance help. In the back I put on 20 inch Blackwaters. I think they are great. They hook up real well, a hug improvement over the Razrs. I will buy them again when I need to replace.I would have like to change them to 22 inch, but I couldn't get the gearing down where I needed, without losing the benefit of the bigger tire. Well, that's my recommendation.
Scott