Military Beadlocks & Runflat Inserts
Most modern military beadlocks and runflats are designed as separate internal inserts and are not directly integrated into the wheel or tire. Whereas traditional beadlock rims rely on a lock ring that bolts over the bead from the outside to clamp it in place, internal beadlock inserts are more akin to a perfectly sized spacer that completely fills the inner void between each bead of the tire.
The simplicity of this design improves their reliability, and the fact that they secure both beads allows for lower operating pressures off-road. However, one notable downside is that the physical width of an internal beadlock is not adjustable, so each insert must be matched to the tire size and wheel-width it was designed for to ensure proper fitment.