Its my first time to own a bimmer. I don't know how it sounds when moving. However, I noticed that at low speeds, there is a humming sound that seems to come from the wheels. As it picks up speed the humming disappears, My mechanic convinced me the bearings on the rear wheels required replacement. I purchased new ones at high cost and replaced them. But I have not noticed any change in the humming! Was I ripped off? My mechanic may tell to replace the front bearings as well without any success and a big hole in my pocket. I have not driven any other bimmer so I have no idea how good bearings work! Any help will help.