Hi ckmorris. Welcome to the forum. Tire wear and a front wheel bearing fit your description. A wheel bearing will sound like an airplane engine and will usually change intensity when turning slightly such as when changing lanes. It can also be hard to tell which side is causing the noise. It can sound like it's coming from one side but actually be transmitted through the body from the other side. Running it in gear on a hoist and listening with a stethoscope is the best way to determine which one is noisy.
Tire wear caused by misadjusted toe, (the direction each individual wheel is steering), can lead to a humming noise on certain road surfaces. This noise will change after rotating the tires. Once on the rear, the tires will eventually wear smooth again but the tires now on the front will develop the same wear pattern if the alignment is not corrected. To identify this cause, your mechanic will "read" the tires to see if the front end is out of alignment. If toe is out of adjustment, each block of rubber will have a raised side that's higher than the other side. You will feel that raised edge by rubbing your hand over the tire tread in one direction, but it will feel smooth in the other direction. An experienced alignment specialist can tell if the fronts of the wheels are too close together or too far apart by which edge is raised. This type of tire wear will always affect both front tires equally provided both are the same manufacturer, tread pattern, and roughly the same mileage. If the two tires are different, they will still show wear but may have different wear pattens.
Tuesday, May 18th, 2010 AT 12:22 PM