A. Original equipment wheel bearings are engineered for a service life of more than 100,000 miles, and many are capable of going twice that distance. Even so, average bearing life can range from 80,000 to 120,000 miles depending on how a vehicle is driven and what the bearings are exposed to.
Wheel bearing cartridges and hubs are sealed and lubed for life so no maintenance is required. But if a vehicle is driven though hub deep water or mud, contaminants may get past the seals and enter the bearing. Once this happens, the bearing is doomed to premature failure. Water breaks down grease, and abrasives scour away at the highly polished bearing surfaces. Eventually, lubrication breakdown and/or wear cause the bearing to fail.
Hard driving, specifically hard cornering, can also shorten the life of front wheel bearings. The ball bearings that are used in many passenger car applications can handle normal driving but not the extreme side forces that can be generated by racing or overly aggressive driving. Police cars and taxis are notorious for eating front wheel bearings depending on how they are driven.
In high-mileage wheel bearings, “fatigue spalling” may result in bearing failure. Fatigue spalling produces tiny cracks in the surface of the rollers and races and allow flakes of metal to break loose. The same type of cracking can also be caused by severe overloading or misalignment in the bearing assembly.
If a wheel bearing has developed looseness or is making noise, it needs to be replaced — the sooner the better, because a catastrophic wheel bearing failure increases the risk of losing a wheel. The same goes for rear axle bearings on rear-wheel drive cars and trucks.
A common symptom of a pending wheel bearing failure is noise from the vicinity of the wheel. The sound may be a whine, hum, rumble, growl, chirp or cyclic squeal that increases in frequency with vehicle speed.
But sometimes, wheel bearings can fail without making a squeak. Any noise that appears to be coming from a wheel should be investigated without delay.
Wheel bearing noise is usually proportional to vehicle speed, and may change when turning, or become louder or even disappear at certain speeds.
A dragging brake pad that’s rubbing against a rotor can often make the same sound, but it usually goes away when the brakes are applied.