I usually run 12lbs. with my 33" BFG Ko's on a 15x8 wheel on a '91 Ho. I've yet to lose a bead at that pressure. I also have an '84 Toyota crawler with 34" swampers on a 15x7 wheel. Forgot the guage and not being used to a bias ply tire we deflated them by "look". Trust me, they dont sink like a radial. They would flex to the rim on every rock and I had the truck at a 45 degree angle at one time with air seeping around the bead, but they never seperated! It was stupid looking with the tire sitting off to one side and the rim pretty much on the rock. Mid-trail we had a guy check the pressure with a digital and it read anywhere from 1.5 to 2.5 lbs per tire! I wouldn't reccomend this, dumb luck helped me not lose a tire but I guess it shows there is some room for error.