Saturn 2009 ASTRA - Manual (Page 241)

Uniform Tire Quality
Grading
Quality grades can be found
where applicable on the
tire sidewall between tread
shoulder and maximum section
width. For example:
Treadwear 200 Traction AA
Temperature A
The following information relates
to the system developed by
the United States National
Highway Traffic Safety
Administration (NHTSA),
which grades tires by treadwear,
traction, and temperature
performance. This applies
only to vehicles sold in the
United States. The grades are
molded on the sidewalls of
most passenger car tires.
The Uniform Tire Quality
Grading (UTQG) system
does not apply to deep tread,
winter-type snow tires,
space-saver, or temporary use
spare tires, tires with nominal rim
diameters of 10 to 12 inches
(25 to 30 cm), or to some
limited-production tires.
While the tires available on
General Motors passenger cars
and light trucks may vary
with respect to these grades,
they must also conform to
federal safety requirements and
additional General Motors
Tire Performance Criteria (TPC)
standards.
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 a half (1.5)
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
driving habits, service practices,
and differences in road
characteristics and climate.
Traction – AA, A, B, C
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.
Vehicle Service and Care 9-57