I've blown an outer bead at least 5-6 times and have seen many other people lose the outer, but have only seen one inner bead lost in my experience. As mentioned above you rarely ever get into a position that would push the inner bead off. The other thing is that on a normal wheel the drop center is on the outer bead, meaning if the outer bead is pushed just past the lip (width of the tire bead) it will pop over the edge and lose the air. The inner bead is much wider, meaning even if you push the tire over the little lip you usually don't pop the bead. On mine and a friends rig we run reverse backspacing wheels. Basically the rim is reversed so the drop center is on the inner bead. It is much harder to lose an outer bead on these wheels. He runs single digit air pressure on a heavy
F-250 with a healthy big block that gets used hard, and have never lost a bead. I lost one bead on my K5 that was pinching the tire just right on a rock.
