Porsche 911 Carrera - Manual (Page 270)

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 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 is based
on braking (straight-ahead) traction tests and
does not include cornering (turned) traction,
acceleration, hydroplaning or peak traction
characteristics.
Temperature A, B, C
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 temperatures 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 B and A represent
higher levels of performance on the laboratory test
wheel than the minimum required by law.
Warning!
The temperature grade for this tire is estab-
lished for a tire that is properly inflated and
not overloaded. Excessive speed, underinfla-
tion, or excessive loading, either separately
or in combination, can cause heat buildup and
possible tire failure, resulting loss of control,
leading to serious personal injury or death.
Tire pressures
Warning!
Incorrect tire pressure causes increased tire
wear and adversely affects road handling.
This could lead to tire failure, resulting in loss
of control, leading to serious personal injury
or death.
Always use an accurate tire pressure gauge
when checking inflation pressures.
Do not exceed the maximum tire pressure
listed on the tire sidewall.
Please observe the chapter ”TIRE PRESSURE
PLATE” on page 327.
Cold tire inflation pressure means: all tires
must be cold, ambient temperature maximum
(68°F /20°C ), when adjusting the inflation
pressure. Avoid sunlight striking the tires
before measuring cold pressures, since
the pressures would rise from temperature
influence.
Valve caps protect the valve from dust and
dirt, and thus from leakage. Always screw
caps tightly down. Replace missing caps
immediately.
Use only plastic valve caps.
268
Practical Tips, Emergency Service