Vehicle care and maintenance
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7
EXAMPLE: DOT MA L9 ABCD 1504
Treadwear, Traction and Temperature Grades
Treadwear
The treadwear 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 one-half (1
1
/
2
) times as
well on the government course as a tire graded 100. The rel-
ative performance of tires depends upon the actual condi-
tions of their use, however, and may depart significantly
from the norm due to variations in driving habits, service
practices and differences in road characteristics and climate.
Traction
The traction grades, from highest to lowest, are AA, A, B
and C. Those 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.
Tem pera ture
The temperature grades are A (the highest), B and C, repre-
senting the tire’s resistance to the generation of heat and its
ability to dissipate heat when tested under controlled condi-
tions on a specified indoor laboratory test wheel. Sustained
high temperature can cause the material of the tire to degen-
erate and reduce tire life, and excessive temperature can
lead to sudden tire failure. The grade C corresponds to a
level of performance which all passenger car 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.
DOT
Department of Transportation
This symbol certifies that the tire is in compli-
ance with the U.S. Department of Transporta-
tion tire safety standards, and is approved for
highway use.
MA
Code representing the tire manufacturing loca-
tion. (2 digits)
L9
ABCD
Code representing the tire size. (2 digits)
Code used by tire manufacturer. (1 to 4 digits)
15
Number representing the week in which the tire
was manufactured. (2 digits)
04
Number representing the year in which the tire
was manufactured. (2 digits)
BK0122500US.book 27 ページ ２０１０年５月１２日 水曜日 午前１１時１１分
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