What Are Rear Wheel Bearings?

Your vehicle contains many components that generate friction as they move, producing heat in the process. Lubricants are essential to reduce this friction, dissipate heat, and prolong the life of these components. Bearings—whether in the wheels or elsewhere—play a critical role in minimizing friction. Without wheel bearings, your car’s wheels would slide rather than roll smoothly. When wheel bearings start to fail, drivers often notice significant changes in handling or noise. Understanding what wheel bearings are, their function, and the signs of a failing front or rear wheel bearing is crucial for vehicle maintenance.

What Is a Wheel Bearing?

A wheel bearing consists of steel balls or rollers housed within a metal ring called a “race,” secured by a cage. These bearings sit inside the hub assembly, which holds the lug nuts that attach the tires to the vehicle. As wheels rotate, friction and heat are generated, and wheel bearings reduce both, protecting the wheels and tires. The hub assembly supports the vehicle’s weight, absorbs road impacts, and allows the wheels to spin freely while turning corners at high speeds.

When Bearings Wear Out

Over time and thousands of miles, wheel bearings naturally wear down due to constant rotation and the vehicle’s weight. Older wheel bearings could be serviced or repacked with grease, but modern vehicles use sealed units to prevent contamination from dust, debris, and moisture. Sealed bearings last longer but cannot be cleaned or lubricated. Once they wear out, the entire wheel bearing assembly—including the hub—is typically replaced to restore proper wheel function.

Signs of Worn Wheel Bearings

When wheel bearings begin to fail, they can no longer allow your wheels to roll smoothly. This increases friction and heat, leading to a rougher, less comfortable ride. If your vehicle shows any of the following signs, it may be time to have your wheel bearings inspected or replaced:

Unusual Noises – Grinding, humming, or growling sounds coming from the wheels are a classic warning sign. Worn bearings cause metal-to-metal contact as the wheel and tire fail to roll properly. These noises usually increase with speed.

Steering Wheel Vibrations – A shaky or vibrating steering wheel can result from several issues, but if wheel bearings are the cause, the vibration is often noticeable at low speeds and can worsen during acceleration if left unaddressed.

Uneven Tire Wear – Faulty wheel bearings can affect wheel alignment, causing uneven tire wear. Ideally, all four tires should maintain consistent contact with the road, but worn bearings can prevent this, creating safety risks—especially on wet or slippery surfaces. Usually, the tire on the side with the defective bearing wears fastest.

Vibrations and Shaky Ride – Increased friction from failing bearings can make your ride feel unstable, producing noticeable tremors and vibrations. These issues persist—and may worsen—until the bearings are replaced.

Excessive Wheel Play – This symptom is typically detected by a technician. While your vehicle is lifted, a technician will try to rock the wheel back and forth. Any wobbling or looseness in the wheel assembly often points to worn bearings.

Driving with damaged or missing wheel bearings is extremely dangerous. Bearings are essential for keeping wheels securely attached to your vehicle. If a wheel bearing fails completely, it could detach, leading to a loss of control and severe accidents—especially at high speeds. Prompt inspection and replacement of faulty wheel bearings are critical to ensuring the safety of both you and others on the road.