In-service catastrophic radial tire failure is often a separation of the tread and outer steel belt from the tire casing and inner steel belt. These separations generally occur in the field at high temperature and high speed. In this study, tire belt-leaving-belt failures were created on a flat-track machine at high speed. The actual separations were captured on high-speed video to locate the origin of the belt-leaving-belt failure. Surfaces corresponding to the gradual cracking of the skim rubber along the edges of the belts, initiation of a belt-leaving-belt separation, high-speed tearing, and termination of the separation were described. The resulting fracture surfaces were then compared with surfaces found on tires that had failed in field service.