Sounds like a sweet ride. I think you are making the right choice but so you know the BGF AT does come in a 305 55 20 as well as a 325 60 20 (I think would require a lift even with the 4x4) as well. Good luck and make sure when you get those tires make the shop cross rotate them every time to eliminate tire cupping which is a common problem with the heavier trucks and AT tires.