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C&B ACTIVE POINT SRL
Bucuresti, Str.Candiano Popescu nr.115
Bogdan Grigore
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Home » Curious facts » Uniform tire quality grade – UTQG

UNIFORM TIRE QUALITY GRADE (UTQG) STANDARDS



The Uniform Tire Quality Grad e is a quality rating system developed by the US Department of Transportation (DOT) that took effect in April, 1979. The system was designed to provide information to consumers as to the relative performance of passenger tires in the areas of tread wear, traction (wet) and temperature. It applies only to automobile tires with a rim diameter of 13" and larger, but not for snow tires and light truck 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. Once a grade is assigned it must be branded on the tire's upper sidewall and printed on its label.


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 for a total of 7,200 miles. The vehicle can have its alignment set, air pressure and tread depth 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. Then the projected worn out tire life is calculated, using 30,000 miles (48,279kms) as 100% Index . The number 100 is assigned as the standard of tread life. As an example, a grade of 150 represents a tread life 50% greater than 30,000 miles (48,300 km), or 45,000 miles (72,400 km).


Traction Grades

The test is performed on wet asphalt and wet concrete road surfaces. The UTQG traction test does not evaluate dry braking, dry cornering, wet cornering, or high speed hydroplaning resistance.


The Traction Grade is determined by installing properly inflated test tires on the instrumented axle of a "skid trailer." The skid trailer is pulled behind a truck at a constant 40 mph over wet asphalt and wet concrete test surfaces. Its brakes are momentarily locked and the axle sensors measure the tire's coefficient of friction (braking g forces) as it slides.


In 1997, the UTQG Traction Grades were revised to provide a new category of AA for the highest performing tires in addition to the earlier A, B and C grades. Previously the A grade had been the highest available and was awarded to tires that offered wet coefficients of traction above 0.47 g on asphalt and 0.35 g on concrete. Today the grades and their traction coefficients are as follows:


Traction
Grades

Asphalt
g force

Concrete
g force

AA

Above 0.54

0.41

A

Above 0.47

0.35

B

Above 0.38

0.26

C

Less Than 0.38

0.26



Temperature (Resistance) Grades

The UTQG Temperature Grade indicates the extent to which heat is generated/ or dissipated by a tire. If the tire is unable to dissipate the heat effectively or if the tire is unable to resist the destructive effects of heat buildup, its ability to run at high speeds is reduced. The grade is established by measuring a loaded tire's ability to operate at high speeds without failure by running an inflated test tire against a large diameter high-speed laboratory test wheel.


Temperature
Grades

Speeds
in mph

A

Over 115

B

Between 100 to 115

C (minimal requirement)

Between 85 to 100




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