UTQG Ratings Explained: Treadwear, Traction, Temperature

What the three grades are

Most passenger car tires carry a line on the sidewall reading something like TREADWEAR 400 TRACTION A TEMPERATURE A. These are Uniform Tire Quality Grading grades, and unlike most sidewall marketing they are defined in federal regulation — 49 CFR 575.104 — which specifies how each is tested and even dictates the explanatory wording that must reach the buyer. Read correctly they are genuinely useful. Read the way they are usually presented, they mislead.

What each grade does and does not tell you

All three corrections below come from the regulation's own text, including a warning it requires be given about the traction grade.

• Commonly claimedA traction grade of AA means the tire grips better.

  VerifiedIt means it stops better in a straight line on wet pavement, and the regulation insists you be told so. The grades run AA, A, B, C and "represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete." The rule then requires this warning: "The traction grade assigned to this tire is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics." So an AA tire is not certified to corner better, resist aquaplaning better, or grip in the dry at all.

• Commonly claimedA temperature grade of C means the tire is poor quality.

  VerifiedC is the legal floor, not a failing mark. The regulation states plainly that "grade C corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Safety Standard No. 109", and that "grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law." The grade measures resistance to generating heat and ability to shed it, on an indoor test wheel. A C-graded tire meets the requirement every passenger car tire must meet.

• Commonly claimedA treadwear grade of 600 means the tire lasts twice as long as a 300.

  VerifiedIt means that on one government test course, under controlled conditions. The regulation's own example is "a tire graded 150 would wear one and one-half times as well on the government course as a tire graded 100" — and it immediately qualifies it: "the relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate." The number is a course-adjusted comparative rating, not a mileage promise, and it is most trustworthy when comparing tires within one manufacturer's range.

How the grades get onto the tire

Section 575.104 requires the grades to be permanently moulded into or onto the sidewall between the tire's maximum section width and shoulder, and separately requires a label affixed to the tread surface of a new tire carrying the same grades in a prescribed layout — treadwear as a number, traction circled from the array AA, A, B, C, and temperature circled from A, B, C. That is why the paper label wrapped around a new tire shows the grades circled rather than printed: the regulation specifies that presentation.

Using the grades sensibly

Treat treadwear as a within-brand comparison and a rough ordering across brands, never as a mileage figure. Treat traction as what it is measured as: straight-line wet braking, which is worth having and is not the whole of wet-weather performance. Treat temperature as a floor check — anything above C exceeds the legal minimum on the lab test. And note what the system does not grade at all: dry grip, cornering, aquaplaning resistance, noise, ride comfort, rolling resistance and snow performance are all outside it, which is why two tires with identical UTQG lines can behave nothing alike.

Related references on this site

The UTQG line is only part of what is written on the sidewall. Our tire size decoder covers the size, load index and speed rating, and the DOT date code guide covers how to work out the week and year the tire was built.

Frequently Asked Questions

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