Humming noise that rises with speed: wheel bearing?

What it means

Wheel bearings let each wheel spin with almost no friction while carrying the car's weight. A failing bearing typically produces a hum or growl, and because it turns with the wheel, the noise is tied to road speed rather than engine speed.

Turning shifts more load onto one side of the bearing, which is why a bearing noise that gets louder when you turn one way is one of the easier faults to recognize by sound.

Common causes

• A wearing wheel bearing, the classic cause
• On an electric car, extra weight putting more load on the bearings
• On a manual car, the gearbox output side or a driveshaft, which also follow road speed

What to do now

1. Note whether the noise follows road speed or engine speed.
2. Notice whether it gets louder when turning, and in which direction.
3. Describe the conditions to the technician: speed, turning or straight, bumps or smooth road.
4. On an electric car, learn the sound well. The bearings carry more weight.

Which noise is it?

• A hum or growl that rises and falls with speed: the classic sign of a wearing wheel bearing
• Louder when turning one way: points further toward a wheel bearing
• A clunk or knock over bumps: bushings, sway bar links or a loose component instead
• Vibration or shimmy in the steering wheel: most often tire balance
• Manual car, noise in neutral that stops when the clutch pedal is pressed: the gearbox input shaft bearing or gear rattle, not a wheel bearing

What people often get wrong

That every noise while driving is the same problem. Turning versus straight, bumps versus smooth road, and whether it changes with speed all narrow the cause down significantly, and a speed-dependent hum points somewhere quite different from a clunk over bumps.

When the car must go to a workshop

Wheel bearing replacement is a job for a professional. A workshop will confirm the source with the car on a lift, since noises from the gearbox output side, a driveshaft and a wheel bearing can overlap.

Read next

• Clunking noise over bumps: what is worn
• Car shakes while driving: what is causing it
• Car making a clicking noise: what the sound tells you

This page is general information and does not replace a professional assessment. Symbols, codes and behaviour vary between makes. Always check the handbook for your own car.