Pontiac 2009 Vibe - Manual (Page 229)

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.
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
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 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.
{ WARNING
The traction grade assigned
to this tire is based on
straight-ahead braking traction
tests, and does not include
acceleration, cornering,
hydroplaning, or peak traction
characteristics.
Vehicle Service and Care 9-57
2009 - Pontiac Vibe Owner Manual