Treadwear Grade vs. Real-World Mileage

The grade is a comparison, not a mileage figure

The UTQG treadwear grade is “a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course.” That is the wording of the federal rule, 49 CFR 575.104. The number has no unit, and it isn’t miles.

The rule’s own example: a tire graded 150 would wear one and a half times as well on the government course as a tire graded 100. By the same logic a 600 grade compares with a 300 grade only on that course, under those conditions.

How the test is run

The rule describes the procedure in detail. In short:

• Tires are run in convoys of two or four vehicles on a roughly 400-mile public road course near Goodfellow Air Force Base in San Angelo, Texas.
• After an 800-mile break-in, the convoy drives 16 circuits, about 6,400 miles, with tires rotated and alignment checked along the way.
• Tread depth is measured in each groove and a wear rate is worked out.
• The result is adjusted using “course monitoring tires” run in the same convoy, to correct for conditions like weather on the course.
• The grade is expressed as a percentage of NHTSA’s nominal treadwear value, rounded down to the nearest step of 20.

The test vehicles are loaded and inflated to set values, and the course is designed to produce wear rates “generally representative” of public use. Your car, roads and habits are not part of the test.

Why your mileage will differ

The rule says it plainly: relative performance “depends upon the actual conditions of their use” and “may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate.”

So no one can turn a treadwear grade into a fixed number of miles. Anyone who does is giving you their own estimate, not a federal rating.

Comparing brands: a note of caution

Tire makers or brand owners grade their own tires using this procedure. The rule requires that each tire be able to achieve the level of performance its grades claim. On this site we show the grades exactly as published in NHTSA’s data, and we flag published values that fall outside the official scale.

Treadwear and the other grades

A high treadwear number says nothing about traction or temperature. Those are separate tests with separate grades. Use our filter tool to set a minimum for all three, or see the highest-treadwear lines with AA traction.

Source

49 CFR 575.104, paragraph (e) and Figure 2. Grades on this site: NHTSA UTQG ratings data (data source).