Your search for the perfect tire can only be improved by understanding the Uniform Tire Quality Grade (UTQG). Don’t let the acronym intimidate you. Created in 1978 to better inform people’s purchase decisions, UTQG rates the performance of tires for three simple qualities—treadwear, traction and temperature resistance.
The rating for a graded tire can be found in any of three places: on the sidewall of the tire, on its retail sticker or in the details listed for the tire online. The UTQG will be a three-digit number plus two sets of letters, such as 500 A A.
Grades are based upon how tires respond to wear under controlled conditions. However, your unique driving style, service routine, climate and road conditions greatly alter a tire’s actual longevity. So while these grades offer an indication of how well a tire holds up, they’re no guarantee that the results will be true for everyone.
This numeric grade is comparative, rating the examined wear of a candidate tire against that of a Course Monitoring Tire (CMT). The tires are driven uniformly in a convoy of rear-wheel-drive vehicles on a 400-mile course of public roads in West Texas for a total of 6,400 miles. The CMT tire has an established grade of 100 and a calculated longevity of 30,000 miles.
A tire that scores 200 can be expected to wear twice as well as the CMT tire, but its mileage won’t necessarily be double. It’s not uncommon for tires with scores ranging from 300 to 700 to both last about 60,000 real-world miles. That’s partly due to the driver variables mentioned earlier, and partly because manufacturers themselves assign the grades.
Depending on how confident a company might be in their product, they may assign a somewhat higher or lower treadwear grade. What prevents manufacturers from grossly exaggerating the expected mileage of a tire is the NHTSA, which oversees the UTQG and can fine anyone who makes overstated claims.
Because all tire companies produce a range of tires including good, better, best performers, the treadwear grade is most useful when comparing products by a single manufacturer—not when comparing products by different manufacturers. For instance, the treadwear rating will let you know which tires are good, better, best among the all-season selection offered by a particular brand.
That said, the most accurate indicator for how many miles a tire will last may be its mileage warranty. Unlike a treadwear grade, a warranty is the manufacturer putting their money where their mouth is. A tire rated 600 AA with a 70,000 mile warranty is quite likely to live up to it.
This letterform grade is determined by a tire’s grip on a wet surface. Candidate tires are uniformly installed on a “skid trailer” equipped with axle sensors. The trailer is brought up to 40 mph on wet pavement, and then the vehicle’s brakes are locked up.
Because the test is performed on skidding tires on wet pavement, the results focus more on the sheer traction of the material and less so on the performance of the tread pattern. The axle sensors strictly measure the tire’s braking g forces.
The highest possible grade of AA is achieved by most ultra-high-performance tires. The vast majority of tires are rated A. Less than a quarter of tires on the market are rated B. And for obvious reasons, it’s not advisable to drive on tires with a C rating.
The second letterform grade reflects a tire's resistance to the generation of heat and its ability to dissipate heat. This in turn establishes a tire’s ability to run at high speeds. The temperature rating is possibly the most critical of all three UTQG grades, because sustained high temperature can cause the material of a tire to deteriorate, and excessive temperature can lead to sudden tire failure.
This test measures a loaded tire’s capacity to run at 375 rpm for 30 minutes, and then at successively higher rates in 25 rpm increments, each for 30 minutes, until the tire has either failed or passed the stage corresponding to its grade. An A is best and means the tire can perform at speeds greater than 115 mph. Even if you don’t plan to ever go that fast, it’s reassuring to know your tire is built to withstand the heat of high speeds, or summer’s hottest day.
In summary, UTQG can really help you rule out options as you search for the perfect tire. But no matter what tires you buy, proper maintenance such as regular tire rotation and air pressure checks will allow your tires to perform and endure their best.
And if the UTQG seems to lack the scope and accuracy you’d like, you’re not alone. The NHTSA has already proposed a broad new consumer information program for tires that would implement a national tire rating system spanning fuel efficiency, safety, and durability.