TM 9-2610-200-14
1-28
SECTION II. EQUIPMENT DESCRIPTION AND DATA (Con't)
1-9. TIRE MARKINGS AND CODES (Con't).
h. SPECIAL PURPOSE CODES (Con't).
(3) DOT Quality Grades for Passenger Car Tires. The Federal Governments Uniform Tire
Quality Grading Standard applies to passenger tires only (but excludes deep tread, winter type snow tires,
temporary use spare tires, and tires with nominal rim diameters of twelve inches or less). Tires subject to
the standard are required to be graded by the manufacturers on the performance factors of treadwear,
traction, and temperature. The grades are molded on the tire sidewall, as shown in the following example
and explained in the following paragraphs.
Example:
TREADWEAR
160
TRACTION
AA*
TEMPERATURE
C
(i) TREADWEAR The treadwear grade is a comparative rating based
on the wear rate of the tire. For example, a tire graded 150 would wear one and a
half (1-1/2) 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 due to variations in use,
maintenance, climate and differences in road characteristics.
(ii)
TRACTION: The traction grades, from highest to lowest, are
AA, A, B, and C, and they represent the tire's ability to stop on wet pavement. A tire
marked C may have poor traction performance.
WARNING
The traction grade assigned to this tire is based on braking {straight ahead)
traction tests and does not include cornering {turning traction).
(iii) TEMPERATURE The temperature grades are A {the highest),
B, and C, representing the tire's resistance to the generation of heat and its ability to
dissipate heat. Sustained high temperature can cause the material of the tire to
degenerate 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.
WARNING
The temperature grade for this tire is established for a tire that is
properly inflated and not overloaded. Excessive speed, under-inflation, or
excessive loading, can cause heat buildup and possible tire failure.
