A wheel bearing is a crucial part of the wheel assembly that connects the wheel and the axle. It is a set of steel balls (ball bearings) or tapers (tapered bearings), held together by a metal ring. It enables the wheel to rotate smoothly with a minimum of friction. Wheel bearings are safety critical components designed to sustain radial and axial loads caused by gravitation, acceleration, breaking & cornering forces, so they need to be replaced when they stop working properly.