Saab 9-3 Convertible M2003, Owner'S Manual

Page: 202 / 256

202 Car care
Uniform Tire Quality Grading (US)
Quality grades can be found where applica-
ble on the tire sidewall between tread shoul-
der and maximum section width. For exam-
ple:
Treadwear 200 Traction AA
Temperature A
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 gov-
ernment 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 driving habits, service
practices and differences in road character-
istics and climate.
Traction
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.
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 dis-
sipate 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. 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.
WARNING
The traction grade assigned to a tire is
based on straight-ahead braking, traction
test and does not include acceleration,
cornering, hydroplaning or peak traction
characteristics.
WARNING
The temperature grade for a tire is estab-
lished for a tire that is properly inflated
and not overloaded. Excessive speed,
underinflation, or excessive loading,
either separately or in combination, can
cause heat buildup and possible tire fail-
ure.
93uC03.book Page 202 Thursday, May 30, 2002 11:36 AM