Yeah, 38 or 39 is what most NC and Ga guys pull, and if you want to run on the interstates in SC. Longer tractors aren't more stable, because they turn over to the sides, not on there backs. We occasionally pulled 40' highside dumps for volume, or to run the interstates, they dumped fine with my tractors. Make sure you keep the tractor straight with the trailer if it is unlevel, particularly wth frame trailers, the articulation of the fifthwheel will get you if you turn too sharp to dump.