A Have the tires rebalanced and rotated once again, making sure the front tires end up on the rear of the vehicle. If this has an effect on the humming noise, the problem is with the tires.
If this doesn't change the noise, the tech may be correct. A front-wheel bearing or hub assembly may be the cause. On most front-wheel-drive vehicles, these are factory-assembled and sealed units that are not serviceable.
Here are two quick checks that can identify a failing hub. Set the parking brake, block the rear wheels and support the vehicle with a jack stand under the suspension. Grasp the tire with gloved hands at the 12/6 position and try to rock the tire and wheel in and out. Any identifiable play in the hub -- not in the suspension or steering -- is cause for concern. Next, turn the key on but do not start the engine, shift the transmission into neutral and turn the key back to the off position. Carefully grasp the front coil spring with one gloved hand and spin the wheel and tire with the other. Often, a worn bearing in a front hub will generate a resonance or vibration in the spring as the wheel rotates.
Q I have a 1999 Pontiac Firebird. Since July, there are times when the radio shuts off and the power windows do not work. Then, after a few seconds or minutes, everything will work again. It is very sporadic. The shop that works on my car is confused because they do not know what to look for when it is working. Why would the radio and windows be connected? I can deal with no radio, but I fear the time when I am stuck with the windows down.
A Have the shop check for any fault codes from the body control module (BCM), then focus on the retained accessory power (RAP) system, which is part of the BCM. The RAP system continues to provide electrical power to the radio fuse (number 17) and power window circuit breaker for up to 10 minutes after the ignition is turned off. The problem could be a poor connection at the BCM or fuse block, a poor ground or a worn connection in the ignition switch itself.
Q I have a 1999 Toyota Solara with 67,000 miles on it. I drive the car only in summers, and the rest of the time it sits in storage. I recently had my oil changed, and the mechanic recommended, given the age of the car, that I replace the timing belt. I thought changing the timing belt had more to do with high miles rather than age of the car.
A Most timing belt replacement recommendations include both a mileage and age component. Toyota recommends replacement on both the inline four-cylinder and V6 engines available in this vehicle at 90,000 miles or 72 months. The good news is that both engines are non-interference engines, meaning no damage outside of the inconvenience and cost of replacing the belt would occur if the belt breaks. Your timing belt is 12 years old, twice the suggested age of replacement; if you plan to keep the vehicle, I'd suggest replacing the timing belt -- and because the timing belt has to be removed to change the water pump, you might think about replacing the 12-year-old water pump at the same time.