This document describes requirements for the inspection and repair of freight, passenger, and infrastructure maintenance rolling stock wheels, providing definitions and illustrations of wheel faults and defects. Each defect category has a severity and corresponding action.

The main purposes of the requirements are to: reduce the risk of derailment arising from wheel failure, reduce the risk of damage to infrastructure caused by wheel defects, minimise hunting/maintaining good vehicle stability and minimise wheel/rail contact stresses in order to prevent rolling contact fatigue in wheels and rails.