Uniform Tire Quality Grading - Tesla X Owner's Manual

Uniform Tire Quality Grading

The following information relates to the tire
grading system developed by the National
Highway Traffic Safety Administration
(NHTSA), which grades tires by tread wear,
traction and temperature performance. Tires
that have deep tread, and winter tires, are
exempt from these marking requirements.
Where applicable, quality grades are found on
the tire's sidewall between the tread shoulder
and maximum section width. For example:
• TREADWEAR 180
• TRACTION AA
• TEMPERATURE A
The quality grades are described next.
Note: In addition to the marking requirements,
passenger car tires must 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 wears one and
a half times better on a government test
course than a tire graded 100. The relative
performance of tires depends on the actual
conditions of their use, however, and can
depart significantly from the norm due to
variations in driving habits, service practices,
road characteristics, and climate.
Traction
The traction grades, from highest to lowest,
are: AA, A, B, and C. These grades represent a
tire's ability to stop on wet pavement as
measured under controlled conditions on test
surfaces of asphalt and concrete. A tire
marked C might have poor traction
performance.
Warning: Defective tires are dangerous.
Do not drive if a tire is damaged,
excessively worn, or is inflated to an
incorrect pressure. The safety of the
vehicle and occupants can be adversely
affected. Check tires regularly for wear
and to ensure there are no cuts, bulges or
exposure of the ply/cord structure.
Warning: The traction grade assigned to
the tire is based on straight-ahead
braking tests, and does not include:
Specifications
Wheels and Tires
acceleration, cornering, hydroplaning or
peak traction characteristics.
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 dissipate
heat when tested under controlled conditions
on a specified indoor laboratory test wheel.
Sustained high temperature can cause the tire
to degenerate and reduce tire life, and
excessive temperature can lead to sudden tire
failure.
The grade C corresponds to the minimum
level of performance that all passenger car
tires must meet under the Federal Motor
Safety Standard No. 109. Grades B and A
represent levels of performance on the
laboratory test wheel that exceed the
minimum requirements.
Warning: A tire's temperature grade is
established for a tire that is properly
inflated and not overloaded. Excessive
speed, under-inflation, or excessive
loading, either separately or in
combination, can cause heat buildup and
possible tire failure.
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