Don't know, but Google gave me this (no idea is this is trust worthy of a bunch of b@#$):
"we forgot to say that most “cheap” beadlock wheels (with cheap being a relative term) and even many expensive wheels are often impossible to balance. This is a big part of the reason that beadlocks aren’t DOT certified. An unbalanced wheel can be extremely dangerous at highway speeds."
"Because most beadlocks from years ago use to lose bolts, which is very dangerous on the highway, because of their constant slight air loss, and the center of the rims were two piece."
"Beadlock rims are considered illegal because of a safety hazard. The way they are placed on tires are by bolts which could become lose. If the bolts become lose then the rim can separate from the tire. "
It would be best to get a DOT link in here... Too lazy to look for one. Someone else will find it!