When I lived in Western Colorado I learned quickly that the best tire for trail running was a pizza cutter. Where I lived the terrain was a mixture of rocks and soil with a lot of clay in it. The soil is also pretty thin, so when it rains the top few inches (maybe more than a few) turns to mud that is more like grease than anything else. The secret to making your way from point A to point B was to dig down to the hard ground for traction. Wider tires had too much flotation, so they would just ride up on top of the "grease", where they couldn't get any bite. I'm sure tire technology has come a long way since those days resulting in wide tires that can get much more traction, but the other problem is that many of the mountain trails are on a side hill which pitches your vehicle way over to the side. If you are floating on top of the grease in that situation, you're sliding off the side of the trail, which is usually really dangerous if not down right inconvenient. Of course this may be old-school thinking, cause I am kinda old-school myself.

So when I move back out there I'm going to think seriously about a trail rig with 9.50's on 7" wheels with 2 1/2" of custom back-spacing from Rocky Road Outfitters and Marlin Crawler's billet wheel spacers of maybe about 1 1/2". -- Matt