I have a 2002 Explorer with 49K using the original tires. The driver-side rear wheel make a low noise at any speed. Any ideas on what the problem may be?

 

A lot of things could cause this noise, but start with the simple stuff first.

At 49K, you are probably at the point where you need new tires, so the first thing I would check is that left rear tire. Does it have any blisters? Is the tread separating? Is it properly inflated? BTW, a blister might cause a side-to-side wobble, especially at low speed.

If the tire looks fine and is properly inflated, you might try swapping it with the spare. If the noise goes away, then the tire was indeed the culprit. Don't replace just one or two - get a set of four.

If the tire's OK, you could have a faulty bearing. Your brake caliper (disc brake) or wheel cylinder (drum brake) could be sticking. Your parking brake may not be disengaging properly. You might have a problem in the differential.

The nature of the noise can be an important clue. Is the sound always the same, or does it sound different at different speeds? Does it change or go away when you apply the brakes?

If you can't figure it out, take it to a shop soon, as this could potentially be very dangerous. A catastrophic failure of a rear wheel, such as a blowout at high speed, may cause your vehicle to fishtail and roll over. That would really ruin your morning!

 

Thanks. The noise is the same at all speeds, though louder at higher speeds. What is a blister? Is it a soft spot or something else. The sound does not change when braking.

 

A blister is like a giant zit on the tire's surface. I had one once in my beloved '78 Chevy Monza. Every time I accelerated from a stop, the car would wobble back and forth. However, that's the least of your worries with a blister. If that bubble bursts like the NASDAQ in 2000, you'll have a blowout. If that happens on the freeway....well, let's just say that it wouldn't be pretty.

Good luck!