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.
eadwear
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
haIf
(
1
1/2)
times
as well on the government course
as
a tire
upon
the
actual conditions
of
their use, however, and
may
depart significantly
from
the
norm
due to variations
b
Oraded
100.
The relative performance
of
tires depends
in driving habits, service practices and differences in
road characteristics and climate.
action
--
A9
The traction grades, from highest to lowest,
are
A,
€3
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 (straightahead) traction tests and does not
include cornering (turning) traction.
~~~~~~~~~~~
-ID
A?
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 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, 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
A
and
B
represent higher levels
of
performance on the
laboratory test wheel than the minimum required by law.
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