The tires are slightly out of balance, out of round, or both. Our suspension was not designed to control the dynamics of 35 inch tires, therefore any off balance in magnafied and transmitted to the whole truck. I'd suggest taking it to a shop that specializes in off road trucks and having them do a good dynamic balance on the tires. Also have them check for an out of round tire while thay are at it. Some folks buy the balancing beads that you put into the tires to help keep the big tires balanced at all speeds; some swear by the beads.

John Luttrell
2001 4x4 short cab, 3 inch lift with 33 inch mudders and Powertrax no-slip in the rear


1991 Jeep YJ, 4 inch suspension lift on 33" BFG's