Wheel Bearing

Most modern cars use sealed hub units with ball or tapered roller bearings. Many include a magnetic ring for the ABS sensor. They are designed to last a long time but can be damaged by potholes and water. Bearings are often pressed into the hub carrier and need special tools to replace.

Rolling elements between inner and outer races carry the weight of the car and side forces in corners.

A humming noise that rises with speed is the classic sign of a worn wheel bearing. Play in the wheel when rocked by hand, or an ABS light caused by a damaged encoder, can also point to the bearing.