Dear Tom and Ray:

Help! My 1994 Toyota Tercel with almost 21,000 miles has developed a strange scratching noise in the rear-tire area. Sometimes it sounds like marbles, pebbles or ball bearings are rolling around intermittently, hitting against metal or plastic. There's no real pattern. Some days it's more pronounced than others. The garage men checked the trunk area, and I removed anything movable. They tightened up the spare-tire "gizmo" and packed around it to prevent it from moving. Then they put it on the lift, checked the brakes and still found nothing. The noise has become more apparent, but still inconsistent. Now they attribute it to bad tires (the original ones). Could that be it? Or are the mechanics fooling this old lady?--Madelyn

TOM: They may not be fooling you, Madelyn. But the first thing they have to do is to make sure it's not a bad wheel bearing. That could be dangerous, so you want to rule that out first.

RAY: Assuming it's not an intermittent wheel bearing noise, it certainly could be a bad tire. Sometimes, when a tire's tread starts to separate, you get a condition known as "tread squirm."

TOM: My brother gets a similar condition when the bill collector comes around to the garage. His name is Fred, and my brother gets "Fred squirm."

RAY: Actually, tread squirm is when the treads separate and get "smooshed" together as the tire turns. It's more likely to happen when the tire is hot, which would explain why it seems intermittent, and as the rubber gets forced together, it makes a sound something like an unhappy, medium-sized rodent. It's somewhere between a series of growls, squeals and grunts. In other words, it could fit your description.

TOM: Here's how you check. Have your mechanic start by moving the rear wheels to the front. If the noise also moves to the front, and you feel a shimmy in the steering wheel at low speeds when you hear the noise, then it's time for new tires. Good luck, Madelyn.