Downloaded from www.Manualslib.com manuals search engine Uniform Tire Quality Grading Treadwe:
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, 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 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.
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 -- A, B, C
The traction grades, from highest to lowest, are A, B,
and C, and they 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 braking (straight ahead) traction tests and does not
include cornering (turning) traction.
- 6-47
