For those of you with BFG 31x10.5x15's, what tire pressure are you maintaining? Max tire pressure is 50psi. I have kept mine at 32-35psi, but was thinking about going up to 40. Any suggestions? Anyone find out what the manufacturer recommends? I bought the tires at a used tire shop so they really weren't any help. I even e-mailed BFG but they never got back to me. Thanks