Mazda 2004 Miata MX-5, Owner'S Manual

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Customer Information and Reporting Safety Defects
Form No. 8S15-EA-03G
Uniform Tire Quality Grading System (UTQGS)
This information relates to the tire grading system developed by the U.S. National
Highway Traffic Safety Administration for grading tires by tread wear, traction, and
temperature performance.
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Tread Wear
The tread wear grade is a comparative rating based on the wear rate of the tire when tested
under controlled conditions on a specified government test course.
For example, a tire graded 150 would wear one-and-a-half times as well on the government
course as a tire graded 100.
The relative performance of tires depends upon the actual conditions of their use, however,
and may depart significantly from the norm because of variations in driving habits, service
practices and differences in road characteristics and climate.
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Traction-AA, A, B, C
The traction grades, from highest to lowest, are AA, A, B, and C. These grades represent
the tire’s ability to stop on wet pavement as measured under controlled conditions on
specified government test surfaces of asphalt and concrete. A tire marked C may have poor
traction performance.
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Temperature-A, B, C
The temperature grades are A (the highest), B, and C, represent the 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 can cause the material of the tire to degenerate and reduce tire
life, and excessive temperatures can lead to sudden tire failure.
Grade C corresponds to a level of performance which all passenger vehicle tires must meet
under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent
higher levels of performance on the laboratory test wheel than the minimum required by
law.
Uniform Tire Quality Grading System (UTQGS)
The traction grade assigned to this tire is based on braking (straight ahead) traction
tests and does not include acceleration cornering (turning), hydroplaning, or peak
traction characteristics.
WARNING
J07S_8S15-EA-03G_Edition2.book Page 14 Thursday, August 21, 2003 10:04 AM