If your car is making a loud hum or howl when you're driving at certain speeds, you may wonder if your wheel bearings need replacing. Most modern front-wheel drive vehicles have wheel bearings that are factory installed and sealed, so they can't be serviced, only replaced, and it's a big job. Some brands of tires can also make a lot of noise that sound similar to bad wheel bearings. Here are some common ways to distinguish between bearing noises and tire noises.
Turning the car affects the noise:
If the noise gets quieter or louder when you make turns, then chances are it's a wheel bearing. Generally, the noise will be louder when you turn in the opposite direction of the wheel with the bad bearing. This means that if the right bearing is bad, then it will get louder as you turn left and quieter as you turn right. This is because you are affecting the amount of load on the bearing when you turn.
The sound changes depending on the road surface or paving:
Tire sounds frequently get louder or softer depending on the road surface or paving type. Some tire brands are louder on hard surfaces, like concrete and quieter on softer surfaces like asphalt and gravel. Surface type usually has little effect on bearing noise unless the surface is bumpy and causes the wheel to bounce.
Your tires are heavily grooved:
If you've ever had to use snow tires, or have a truck or SUV with heavily treaded tires, then you know that these tires are noisier than the average car tires. Some all-season car tires can also be noisy depending on their tread depth. Certain types of tire wear can also affect tire noise. You may notice an increase in noise for this reason after your tires are rotated. You can try switching tires to see if the noise will go away. If it doesn't then you might have to look into checking out other components such as your wheel bearings.
Be aware that some cars won't exhibit any symptoms of a bad wheel bearing until it's so worn down that your wheels began to wobble and vibrate. Don't ignore any wheel noises and if you're not sure what the noise might be, take your car in for service and have a car repair mechanic look at it. If it's a wheel bearing, get it replaced as soon as possible as a bad bearing can seize up and affect your driveability and steering, making your car unsafe to drive.