Question: I have a 1983 Seville with 19,000 miles on it. At 10,000 miles, the outside of the right rear tire started to wear out. I took it to a garage, and the mechanics claimed they would put in a shim with a certain degree of taper. Now the same tire is nearly bald, indicating the problem has not been remedied. What is your feeling about this?--J.N.
Answer: The repair you describe may not be an authorized General Motors warranty procedure, but it is a repair that is sometimes done. Wedge-shape shims are available on the auto-parts after-market for aligning certain cars, including some Cadillacs.
The problem is that Cadillac did not make provisions for adjusting the camber on the rear end of the Seville, which is a front-wheel-drive car. Many front-wheels-drive cars have rear ends that may go out of alignment, but they lack the hardware that permits alignment.
Camber determines the angle at which the tire rides on the road, and an out-of-adjustment camber will cause a tire to wear out on one side.
A toe adjustment, which makes sure both wheels are pointed in the same direction, is possible on the Seville rear end, but the wear pattern on your tire indicates that the camber is wrong.
Apparently Cadillac thought its cars would never go out of alignment. But they do, according to alignment experts. The only alternative to the shims would involve straightening a bent frame. It's unlikely, however, that your frame is bent.
For a job such as yours, you need a top-notch front-end shop, not some discount car-repair garage that specializes in high-volume work. You said you believe the shim did not solve the problem, but you can't be certain. Once an irregular wear pattern has been established on a tire due to an alignment problem, the tire is likely to continue wearing in that pattern even after the alignment is corrected.
Ralph Vartabedian cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.