Often times, customers ask about the UTQG rating on tires. The UTQG ratings were designed to provide consumers with useful information to help them purchase tires based on their relative treadwear, traction and temperature capabilities.
Treadwear is a rating on how long the tire should last; the higher the number, the longer the life of the tire in theory. Traction is rated on a scale similar to grades in school (C, B, A), but instead of an A+, there's AA at the top. Temperature rating is rated C, B or A (again with A being the highest).
The tests to determine these grades are run in standardized conditions, so every manufacturer runs the same tests on their tires. Treadwear is judged after only 7,200 miles, so there is a good amount of extrapolation done here, and this is all done by the manufacturers on their own tires. The traction grading is based on the straight-line wet coefficient of friction of a tire. The traction grade in UTQG does not indicate, in any way, the dry traction, cornering, or hydroplaning resistance. It only refers to the tire's kinetic friction at 40 mph while attached to a trailer that locks its brakes momentarily and measures braking g-forces. Manufacturers then decide from that measurement whether they give it an AA, A, B or C. Temperature is basically a tire's ability to run at high speeds under load without melting or blowing up. They test it in a lab and see how hot it gets under load to see what speed the tire can withstand without failing due to overheating.
My general rule of thumb for UTQG is unless you're using it to compare two tires from the same manufacturer, in the same performance category, then UTQG isn't something to use for the average consumer. We have several options on our website that can help you compare tires, such as tire tests and consumer surveys.
For a more detailed understanding of UTQG, read "Uniform Tire Quality Grade (UTQG) Standards."