Question: A tire dealer recently told me that the radial tire on my rear wheel has become separated. I took the car in because it was squirming down the road. Exactly what did he mean by separation, and can it be repaired? What causes tires to separate?--M.S.
Answer: A radial tire is a sandwich that is usually made of a cord body, steel belts and rubber tread. Separation occurs when either the steel belts come loose from the cord body or when the rubber tread comes loose from the steel belts.
In either case, separation is a serious condition and almost always means that the tire has reached the end of its life, no matter how much rubber tread is left.
A separation usually throws the tire grossly out of balance, resulting in a heavy thumping noise as you drive down the road or the squirming sensation that you describe.
Although the tire may look normal when it is on the car, once it is removed you can clearly see that the tire is out of round. Sometimes the separation manifests itself as a large bubble on the tread or the sidewall.
Another indicator of separation is something known as a mole hole, which is a knot or bump on the sidewall that results from distortions of the cord body or the belts. Mole holes, which look just like a mole or gopher hole in the ground, are about the size of your fingernail.
Unfortunately, there is no way to repair a separation, because the damage has occurred in the very foundation of the tire. You should check your tire warranty, however, because such failures may be covered under the workmanship clause.
Separation can be caused by many things, such as poor overall quality or excessive tread wear. Sometimes, a puncture can damage the cord body, and even though the tire is repaired initially, the damaged cords will eventually allow separation. Another cause is worn suspension parts, such as struts, which allow a cupped wear pattern that puts a lot of stress on the tire.
Tires have been vastly improved in their ability to resist blowouts or other sudden losses of air pressure. But separations sometimes are a precursor to blowouts, which are among the most dangerous mechanical mishaps you can experience at highway speeds.
Aside from safety reasons, consider the possibility that the tire could throw off a steel belt or tread that could rip up your fender well and cause hundreds of dollars worth of damage.
Q: I have a problem on my 1987 Honda Accord. The power window on the front-passenger side seems to go down slower than the other windows. I took it to the dealer, but after a day of work it wasn't any better than when I took it in. What's the matter?--R.D.
A: Honda has recognized that it has a problem with these windows. When you hit the window switch from the driver's position, the wiring is such that the current has to travel around the car to the window and then back again.
This long distance results in a voltage drop, which causes the window to labor. The wire gauge is not adequate to handle the load. In the 1988 Accords, Honda has increased the gauge of the wire and put a bigger motor in.
The company has issued several bulletins on repairing the condition, which involves attempting to get the window to move more smoothly on its track. That reduces the load on the motor.
It requires some skill to perform the work, however, because the door frame has to be bent manually to change the track. You might try going to a different dealer or a different mechanic because it is still under warranty.