What a UTQG rating is
UTQG stands for Uniform Tire Quality Grading. It is three grades on a passenger car tire, for example 400 A A: treadwear, traction and temperature. The tests and grades are set by the federal rule 49 CFR 575.104.
Treadwear
The treadwear grade is relative. Tires are run on a government test course and graded against each other: in the rule's own example, a tire graded 150 wears 1.5 times as well as a tire graded 100. Grades come in multiples of 20, so 400 and 420 are valid grades and 410 is not.
relative wear = treadwear of tire B ÷ treadwear of tire AWorked example: 600 ÷ 400 = 1.5, so on the government course a tire graded 600 wears 1.5 times as well as one graded 400. The rule itself warns that real wear depends on use and can differ a lot from the test because of driving habits, maintenance, road surfaces and climate. A treadwear grade is not a mileage figure, and this page does not turn it into one.
Traction
The traction grade comes from straight-ahead braking on wet asphalt and wet concrete test surfaces, and nothing else. To earn a grade, the tire's adjusted braking coefficient must be above both values. A C grade means the tire did not reach the B values on at least one of the two surfaces.
| Grade | Wet asphalt, above | Wet concrete, above |
|---|---|---|
| AA | 0.54 | 0.38 |
| A | 0.47 | 0.35 |
| B | 0.38 | 0.26 |
| C | 0.38 or less | or 0.26 or less |
Temperature
The temperature grade comes from a laboratory test on a test wheel. C means the tire meets the minimum set by FMVSS 109. B means it also passes the test-wheel stage at 500 rpm, and A the stage at 575 rpm. The rule defines the grades by these test stages, not by road speed, so this page gives no mph figure for them.
Tires without a UTQG grade
UTQG applies to passenger car tires only. It does not apply to deep-tread winter tires, temporary spare tires, tires for rims of 12 inches or less, or limited production tires. A tire without the grades may simply be outside the rule.
How to use the calculator
Type the three grades in order, with or without spaces: 400 A A, 400AAA and Treadwear 400 Traction A Temperature A all work. Leave tire 2 empty to read one tire on its own.
Comparing two tires
Enter both ratings. The calculator divides the treadwear grades and says which tire is graded higher for traction and for temperature. A treadwear grade that is not a multiple of 20 is flagged as not a valid grade: check the digits on the tire.
Questions
What does UTQG mean on a tire?
Uniform Tire Quality Grading: three grades set by 49 CFR 575.104. In 400 A A, 400 is the treadwear grade, the first A is traction and the second A is temperature.
What does the treadwear rating mean?
It is relative to the government test course: a tire graded 600 wears 1.5 times as well as one graded 400 there. Real wear depends on driving habits, maintenance, roads and climate.
Is AA traction better than A?
AA is the highest traction grade: a wet braking coefficient above 0.54 on asphalt and above 0.38 on concrete, against 0.47 and 0.35 for A. It covers straight-ahead wet braking only.
How many miles is a 500 treadwear rating?
The rule gives no miles, and this page does not convert treadwear into miles. On the government test course, a tire graded 500 wears 5 times as well as one graded 100.