Treadwear rating
Encyclopedia
The Treadwear Grade of a tire
is the numeric portion of the Uniform Tire Quality Grade Standards (UTQG)
that are printed on the sidewall of a tire. These standards were enacted by the National Highway Traffic Safety Administration (NHTSA)
, which is part of the United States Department of Transportation
. Higher treadwear numbers indicate that the tread
of a tire, and hence the tire itself, should last longer.
. Both types of tires are mounted on vehicles that will be driven in a convoy
during the test, thus ensuring that the candidate tires and the CMT tires experience the same road conditions. The convoy, typically one of four or fewer vehicles, will drive 7200 miles on public roads in West Texas
. Candidate tire wear will be checked during and after the test, and compared to the wear on the CMT tires from the same convoy.
The first CMTs were commercially-available Goodyear Custom Steelguards, and Goodyear Tire and Rubber Company
produced all CMT tires from 1975 until 1984. From 1984 to 1991, the CMT tires were produced by Uniroyal. CMT tires are now "specially designed and built to American Society for Testing and Materials (ASTM)
standard E1136 to have particularly narrow limits of variability." 1.
Please note: As Course Monitoring Tires have changed, their treadwear grades have changed to numbers considerably higher than 100. As a result, it would be incorrect to say that a tire with a treadwear grade of 200 gets twice the life of the Course Monitoring Tire.
The assigning of UTQG grades is done solely by the tire manufacturer. In many cases, this has resulted in the UTQG grading system to be more of a marketing tool than was originally intended.
It is legal and permissible for a tire manufacturer to give a particular tire line a lower treadwear grade. For example: If the highest treadwear grade in a manufacturer's line up is 600, then a tire line with a lower treadwear test result might receive a grade of 400, instead of the 480 it could possibly receive.
Also, it is common for tires whose treadwear grade is of little commercial value, such as "DOT" racing tires, to be assigned extremely low values - sometimes even zero.
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
is the numeric portion of the Uniform Tire Quality Grade Standards (UTQG)
UTQG
UTQG stands for Uniform Tire Quality Grading.The National Highway Traffic Safety Administration established the Uniform Tire Quality Grading Standards in 49 CFR 575.104.- Treadwear :...
that are printed on the sidewall of a tire. These standards were enacted by the National Highway Traffic Safety Administration (NHTSA)
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
, which is part of the United States Department of Transportation
United States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...
. Higher treadwear numbers indicate that the tread
Tread
The tread of a tire or track refers to the rubber on its circumference that makes contact with the road. As tires are used, the tread is worn off, limiting its effectiveness in providing traction. A worn tire tread can often be retreaded. The word tread is often used incorrectly to refer to the...
of a tire, and hence the tire itself, should last longer.
Methodology
The wear on tires that are being tested ("candidate tires") is compared to the wear of Course Monitoring Tires (CMT), which are sold by the NHTSA at its UTQG test facility in San Angelo, TexasSan Angelo, Texas
San Angelo is a city in the state of Texas. Located in West Central Texas it is the county seat of Tom Green County. As of 2010 according to the United States Census Bureau, the city had a total population of 93,200...
. Both types of tires are mounted on vehicles that will be driven in a convoy
Convoy
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support, though it may also be used in a non-military sense, for example when driving through remote areas.-Age of Sail:Naval...
during the test, thus ensuring that the candidate tires and the CMT tires experience the same road conditions. The convoy, typically one of four or fewer vehicles, will drive 7200 miles on public roads in West Texas
West Texas
West Texas is a vernacular term applied to a region in the southwestern quadrant of the United States that primarily encompasses the arid and semi-arid lands in the western portion of the state of Texas....
. Candidate tire wear will be checked during and after the test, and compared to the wear on the CMT tires from the same convoy.
The first CMTs were commercially-available Goodyear Custom Steelguards, and Goodyear Tire and Rubber Company
Goodyear Tire and Rubber Company
The Goodyear Tire & Rubber Company was founded in 1898 by Frank Seiberling. Goodyear manufactures tires for automobiles, commercial trucks, light trucks, SUVs, race cars, airplanes, farm equipment and heavy earth-mover machinery....
produced all CMT tires from 1975 until 1984. From 1984 to 1991, the CMT tires were produced by Uniroyal. CMT tires are now "specially designed and built to American Society for Testing and Materials (ASTM)
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
standard E1136 to have particularly narrow limits of variability." 1.
Treadwear Grade Number
The Treadwear Grade describes how a tire manufacturer views the wear of a given tire. In theory, this means that a tire with a 200 grade will wear twice as long as a tire with a 100 grade. However, tire manufacturers are not under any obligation to grade a tire based on the test results, except to say that they can not overstate the grade. This is enforced by NHTSA requiring documentation to justify any assignment of a grade on a tire.Please note: As Course Monitoring Tires have changed, their treadwear grades have changed to numbers considerably higher than 100. As a result, it would be incorrect to say that a tire with a treadwear grade of 200 gets twice the life of the Course Monitoring Tire.
Limitations
Notice that the treadwear grade is a ratio and not a mileage. This is because there are a lot of factors that determine treadwear rates and most of them are a function of driving conditions and operating environment, and not the tire itself. As a result, actual tire wear will vary considerably within the same tire line. The phrase "Your mileage may vary" applies here.The assigning of UTQG grades is done solely by the tire manufacturer. In many cases, this has resulted in the UTQG grading system to be more of a marketing tool than was originally intended.
It is legal and permissible for a tire manufacturer to give a particular tire line a lower treadwear grade. For example: If the highest treadwear grade in a manufacturer's line up is 600, then a tire line with a lower treadwear test result might receive a grade of 400, instead of the 480 it could possibly receive.
Also, it is common for tires whose treadwear grade is of little commercial value, such as "DOT" racing tires, to be assigned extremely low values - sometimes even zero.