This SAE Recommended Practice establishes uniform engineering nomenclature for wheels, hubs, rims, and their components used in truck, bus, and trailer applications. This nomenclature and accompanying drawings are intended to define functional truck wheel, hub, and rim designs. For nomenclature specific to “passenger-type” disc wheels, refer to SAE J1982. The International Standard (ISO) nomenclature is shown in parentheses when different than SAE J393.