Non-Axle Noise

There are a few other conditions that may sound like axle noise and must be considered in pre-diagnosis.

The most common are exhaust, tires, and trim moldings.
^ In certain conditions, the pitch of the exhaust may sound very much like gear whines. At other times, it can be mistaken for a rear wheel bearing rumble.
^ Tires, especially snow tires, can have a high-pitched tread whine or roar similar to gear noise. Radial tires, to some degree, have this characteristic. Also, any non-standard tire with an unusual tread construction may emit a roar or whining noise.
^ Trim, grille and moldings can also cause whistling or whining noises.

Make sure none of these are the cause of the noise before proceeding with an axle teardown and diagnosis.