Wheel bearings are an important part of an automobile's suspension. Located between the hub (which carries the wheel) and the suspension's spindle or axle, the bearing ensures that the wheel rotates smoothly and stays in the same position.
A wheel bearing is a circular row of small ball bearings that are pressed together in a housing. The ball bearings provide the spinning motion for the wheel.
Wheel bearings are usually pretty isolated from dirt with some type of cap or seal, but they can become contaminated. If this happens the bearings can get scored and damaged.
The wrong wheels for a particular suspension design can cause the bearings to fail from the excess load being placed on them. This will usually be from wheels that stick out too far from the suspension because of an aggressive, incorrect offset.
Wheel bearings can fail from simply being used for too many years. Wheel bearings should be inspected every few years.
A bad wheel bearing can make rubbing noises if it is failing. A bad bearing can also cause a vague and twitchy response from the steering.
Inspect your bearings regularly or have them inspected. With the car jacked up, attempt to move the move the wheel fore and aft by rocking the top and bottom. There should be no movement. Also make sure the bearings are packed with bearing grease.
