THE GOODS : Car Owner Tires of Uneven Tread Wear
Question: The tires on my 1993 Ford Taurus appear to be wearing out very quickly. The wear is occurring on the left and right edges of both front tires. My mechanic says this is caused by underinflation, but I have kept the inflation right at the 32 pounds Ford recommends and I have kept the tires rotated. The tires only have 31,000 miles on them and I sure don’t want to spend $400 on a new set. What is causing the problem? R.R.
Answer: Your kind of problem gives tire engineers indigestion. Diagnosing premature tire wear is a tricky task because so many different factors affect the life of tire tread.
In extreme cases, some models of cars just seem to eat up tires, while other models go indefinitely on the originals. Some cars can never hold a proper alignment, while others never need alignment.
Your mechanic is correct that exaggerated wear on the tire shoulders (edges) is a sign of underinflation. If you keep too little air pressure in a tire, the shape changes. The center collapses a tiny bit, allowing more of the car’s weight to fall on the shoulders.
But shoulder wear can be caused by other factors. When Ford engineers selected your tires and designed the Taurus suspension system, they had to balance the vehicle for different types of driving by different owners.
A lot of driving around town with many turns will cause more shoulder wear. The same is true of quick starts and stops. By contrast, a lot of highway driving will cause relatively more wear on the center of the tires. So, the extra wear you are seeing could be an indication that you are simply driving more than average in town or driving in an aggressive fashion.
Another possibility is that the tires are simply of the type that wears out on the shoulders first. Just because the tires don’t wear evenly doesn’t necessarily mean you are getting cheated out of tread life.
But you should expect more than 31,000 miles out of a set of new tires. It is impossible to say how long tires should last, but a set of new tires properly inflated and rotated should go a bit farther than 30,000 miles. In some cases, original tires go past 100,000 miles.
You can experiment a little with tire inflation, adding a few pounds of pressure, according to tire engineer Jim Knowles of Michelin. But be sure not to go above the maximum recommendation inflation listed on the sidewalls. And be forewarned that the extra air may affect the ride and handling.
Before experimenting with the tire pressure, you will want to be sure the tires are correctly aligned. And you also want to be sure that the tire pressure gauge you are using is accurate. Many cheaper gauges give out inaccurate readings.
* Vartabedian cannot answer mail personally but will attempt to respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, 1875 I St. N.W. #1100, Washington, D.C. 20006.
