If you have the tow package with the 3:92's stay in the 8500 range. People will say to add up this and that, but the rating is around 8500 minus passengers and cargo. The truck doesn't like much over 8k anyway once you hit any hills. I feel the brakes and suspension are more then enough for 9k, but unless you are running a cam, 8k is the top of the comfort zone for the motor for extended trips.