How is the treadwear grade determined?
Treadwear tests are performed on a government-prescribed 400-mile section of public highways near San Angelo, Texas. Test vehicles travel the same course at the same time, so all tires experience the same conditions. During the test, tread groove depths are measured every 800 miles. The same procedure is followed with a set of reference control tires. After 7200 miles of testing, the tread depths of test tires and reference control tires are compared and the test tires are graded on the basis of relative wear.
