Tire testing by the numbers

Gene Petersen, Jen Stockburger, and Ryan Pszczolkowski could probably land spots on a pit crew if they ever chose to leave Consumer Reports. The three of them do the bulk of our tire testing at our Auto Testing Division, which means, among other things, performing some 2,600 tire changes last year alone. That's enough to routinely wear out the studs that hold lug nuts to the hubs--despite  liberal doses of silicone and careful torque wrench use. Few cars will ever see anywhere near 2,600 tire changes between the assembly line and the scrap heap. But then again, most magazines don't buy several hundred tires for testing every year.

Regular readers know that Consumer Reports conducts the most thorough car testing program of any magazine or Web site in the United States, but even CR junkies may not realize how extensive our tire-testing program is.

For the last report, we bought 572 tires, including duplicate sets and spares. To minimize damage to the tires from changing, we also bought 150 identical wheels. The goal is to have all the tires in-house by November, to give us a couple of months to catalog and mount them. By January, we're ready to begin.

One car was bought new specifically for the tire testing program this year, an Audi A3 for performance-tire testing. Last year it was a Honda Accord for all- season tires. Each car quickly ran up close to 14,000 miles, mostly at our track.

These are some hard miles. Days of hard braking, handling tests, flat-out acceleration and circling the skid pad in all kinds of weather take their toll on the cars, as well as the tires. The cars routinely wear through at least one set of brake pads before the six months of testing are through, and they've also worn out brake master cylinders, suspension parts, and at least one transmission.

When all is said and done, the tire test car will have made more than:

• 430 trips through our avoidance maneuver course. (Note to Gene, Jen, and Ryan: Light breakfast.)
• 860 laps around the skid pad. (Skip lunch.)
• 1450 stops from speed in the dry, wet, and even on ice. (Maybe just start fasting altogether.)

But the really big number comes from our wear testing, which helps determine how long you can expect the tires to last on your car. In 2006, we racked up a grand total of 1,120,000 miles.

At least the wear testing can be done on a full stomach.

—Jim Travers