Trail pressure also varies by the type of tire you have, an MT or AT. With my 33x12.50's AT's on 10" rims I run them at 12psi on rock trails and fire roads(makes fire roads as smooth as the highway) while my buddies running MT's in various sizes run at 8-10. The lower pressure for the MT's is to get the side walls to flex better(they are stiffer to start with than AT's). In the snow I will run as low as 1-2 psi. w/o beadlocks <img src="/forums/images/graemlins/scared.gif" alt="" /> , same for my buddies running the MT's. On the highway I run my AT's at 35psi(max rated pressure) and I get perfect tire wear, however my truck also weighs 1000+lbs over stock. As mentioned to get the best wear and right tire pressure for the road do the chalk test, for the trail run whatever pressure is nec. to get the job done.