We have a 2008 Isuzu NPR 6.0 Gasser. Has about 15k on it. I have no idea why ALL of the tires are choppy! Please don't be mislead, it's not horrible, but getting there! I keep everything greased, what else should I be doing? I talked with someone who has or has had the Isuzu line before we purchased it and he mentioned they "go through rubber." Any thoughts or suggestions? ***I can't move the front to the back like we do on the pick-up becase of the different rim style.