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3-5) Uniform Tire Quality Grading System(UTQGS) |
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The Uniform Tire Quality Grading System is a labeling system required by the U.S. federal government. All passenger car, minivans and pickup truck tires sold in the United States must be graded and labeled with information concerning tread wear, temperature (resistance to heat build up) and traction. These ratings are intended to help consumers more easily compare tires. Manufacturers that sell tires in the United States must pass a series of tests promulgated by NHTSA (National Highway and Traffic Safety Administration). Based upon the test results, manufacturers are then responsible for assigning grades to their products.
Treadwear
Treadwear grade is a rating based on the relative wear rate of tires when tested for 6,000 miles under controlled conditions on a specified NHTSA test course. In tire grading, for instance, a 150 rating means a tire could wear one and a half times as well on the government course as a tire graded 100. Remember, however, that wear performance may also depend on an operator's driving characteristics and road conditions.
Traction
Traction grades are AA (the highest), A, B and C. The rating is based on a low-speed (40mph) wet braking test and generally indicates the traction capability of the tread compound in straight -ahead braking. Due to the low speed and relatively rough test surface, results are not greatly affected by the tread patterns. Also, the grade does not indicate the tire's relative ability to generate cornering force or to resist hydroplaning.
Temperature
The temperature grades are A (the highest), B and C. They indicate a tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel.
Sustained high temperature (e.g. driving long distances in hot weather) can cause the material of the tire to degenerate and reduces tire life. Excessive temperature can also lead to sudden tire failure. The grade C corresponds to a level of performance that all passenger car tires must meet under NHTSA's standards. Grades A and B represent higher levels of performance on the laboratory test wheel than the minimum required by law. |
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3-6) Run flat tire |
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A "run flat tire" can be driven up to a limited mileage at a limited speed at low or zero air pressure.
The following are typical types of "run flat tires".
Self-Supporting Technology (SST) Tire
The sidewall is reinforced by thicker rubber. Even if the air pressure is low or zero, the vehicle's load is supported by the reinforced sidewall.
This SST tire has good handling performance even if all air pressure is lost.
A normal rim can be used with the SST tire. The SST tire requires a TPMS( Tire Pressure Monitoring System).
PAX system (Supporting ring system)
PAX system comprises a tire, a rim, a support ring and a tire pressure monitoring system.
The support ring surrounds the rim. When the air pressure is low or zero, the vehicle load is supported by the ring . The PAX system can be adopted for a tire with a bigger Load Index than a standard (regular) tire.
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