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The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration's (NHTSA) Uniform Tire Quality Grade Standards (UTQG) were originated to provide consumers with useful information to help them purchase tires based on their relative treadwear, traction and temperature capabilities. While it is required by law for most passenger car tires sold in the United States, it is not required for deep treaded light truck tires, winter/snow tires, temporary spare tires, trailer tires, tires under 12” in diameter and other select tires.
When looking at UTQG ratings it is important to realize that the Department of Transportation does not conduct the tests. The grades are assigned by the tire manufacturers based on their test results or those conducted by an independent testing company they have hired. The NHTSA has the right to inspect the tire manufacturer's data and can fine them if inconsistencies are found. While most new tire lines have their grades established when they are introduced, they are allowed a 6-month grace period to allow the tire manufacturer to test actual production tires. Once a grade is assigned it must be branded on the tire's upper sidewall and printed on its label.
Unfortunately, the rating that is of the most interest to consumers is the one that appears to be the least consistent. While the Treadwear Grade was originally intended to be assigned purely scientifically, it has also become a marketing tool used by manufacturers to help position and promote their tires.
Treadwear Grades
UTQG Treadwear Grades are based on actual road use in which the test tire is run in a vehicle convoy along with standardized Course Monitoring Tires. The vehicle repeatedly runs a prescribed 400-mile test loop in West Texas for a total of 7,200 miles. The vehicle can have its alignment set, air pressure checked and tires rotated every 800 miles. The test tire's and the Monitoring Tire's wear are measured during and at the conclusion of the test. The tire manufacturers then assign a Treadwear Grade based on the observed wear rates. The Course Monitoring Tire is assigned a grade and the test tire receives a grade indicating its relative treadwear. A grade of 100 would indicate that the tire tread would last as long as the test tire, 200 would indicate the tread would last twice as long, 300 would indicate three times as long, etc.
The problem with UTQG Treadwear Grades is that they are open to some interpretation on the part of the tire manufacturer because they are assigned after the tire has only experienced a little treadwear as it runs the 7,200 miles. This means that the tire manufacturers need to extrapolate their raw wear data when they are assigning Treadwear Grades, and that their grades can to some extent reflect how conservative or optimistic their marketing department is. Typically, comparing the Treadwear Grades of tire lines within a single brand is somewhat helpful, while attempting to compare the grades between different brands is not as helpful.
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The Bridgestone RE050 have a 140 UTQG rating
I got 45,000km out them on a Mazda3 SP23
They have great grip, turn in and braking - and last very well
When it's wet, you need to get some heat into them before pushing hard (into corners and braking)
But you will find they exaggerate axle tramp on most FWD cars (not the fault of the tyre, shows grip)
I'll keep that in mind when they are finally on the vehicle.
