Why is there a humming noise that gets louder with speed?
A hum or growl that gets louder as you go faster, and doesn't change when you shift gears or rev the engine, is usually a worn wheel bearing or tires with uneven wear. A wheel bearing noise often changes when you weave gently left and right at speed. A failing wheel bearing should be replaced soon; in the worst case it can affect steering and braking.
Bearing or tires?
| Clue | Wheel bearing | Tire wear |
|---|---|---|
| Rises with speed | Yes | Yes |
| Changes when weaving left and right | Often | Rarely |
| Changes on different pavement | Less | Often |
| Visible sign | Play in the wheel on the lift | Cupped or feathered tread |
| Other symptoms | ABS light on some cars, grinding | Vibration, a pull |
Why it happens
Wheel bearings wear with mileage, potholes, curb strikes and water getting past their seals. Tires wear unevenly when alignment is off, suspension parts are worn, or rotations are skipped, and uneven tires drone loudly.
What we do
We road test, inspect the tires, and check each wheel for play and roughness on the lift. If it's the tires, we'll also find why they wore that way, so new ones don't do the same.
More questions
How do I tell a wheel bearing from tire noise?
Tire noise often changes on different road surfaces and can be seen as cupped or uneven tread. A bearing usually gets louder when you turn one way and quieter the other, because weight shifts onto or off it.
How long can I drive on a bad wheel bearing?
A faint hum may last a while, but it's unpredictable. If it's loud, grinding, or you feel play or vibration in the wheel, get it replaced right away.
Which side is the bad bearing on?
If the noise gets louder turning left, the right-side bearing is usually the one being loaded, and vice versa. We confirm on the lift.