I used to run 38" SX's on my truck. I recently sold them so I could buy a tire that was actualy round. I dont know if I got a bad set or what, but they never smoothed out. I ran mine at around 20 psi to try and get decent tread contact so that probably didnt help the flat spotting, but if you ran them at any higher psi they would hardly be riding on any tread. As it was it only rode on the center lugs. They may be a great tire off road, I never got a chance to try them out, but imo they suck on road.