Porsche 718 Spyder, Руководство пользователя

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219
Tires and Wheels
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Uniform Tire Quality Grading
Fig. 193: Treadwear, Traction and Temperature of the tire
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. All passenger vehicle tires must
conform to Federal Safety Requirements in addition
to these grades. Quality grades can be found where
applicable.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specific 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.
f
Please see chapter „Checking tire tread“ on
page 224.
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.
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 vehicle tires must meet under
the Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of perfor-
mance on the laboratory test wheel than the
minimum required by law.
Glossary of tire terminology
Radial ply tire
A pneumatic tire in which the ply cords which extend
to the beads are laid at substantially 90° to the
centerline of the tread.
Ply
A layer of rubber-coated parallel cords.
Cord
The strands forming the plies in the tire.
Rim
A metal support for a tire or a tire and tube assembly
upon which the tire beads are seated.
Bead
The part of the tire made of steel wires, wrapped or
reinforced by ply cords, that is shaped to fit the rim.
Sidewall
The portion of a tire between the tread and the bead.
Information
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.
WARNING
Tire Abuse
The temperature grade for this tire is established for
a tire that is properly inflated and not overloaded.
Excessive speed, underinflation, or excessive loading,
either separately or in combination, can cause heat
buildup and possible tire failure.
e
Do not exceed the permitted maximum speed for
the tires fitted to the vehicle.
e
Ensure that the tires are set to the correct infla-
tion pressure.
e
Observe the maximum load for the vehicle.
21_718_GT4_Spyder_BAL_21_WKD 982 02 21 21_KW36.20-24.21_en_US.book Seite 219 Freitag, 24. Juli 2020 11:31 11