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•
Higher - to allow higher load carrying
capacity and to allow it to travel over
rough terrain without getting hung up or
damaging underbody components.
• Shorter - to give it the capability to
approach inclines and drive over the
crest of a hill without getting hung up or
damaging underbody components. All
other things held equal, a shorter
wheelbase may make your vehicle
quicker to respond to steering inputs
than a vehicle with a longer wheelbase.
• Narrower - to provide greater
maneuverability in tight spaces,
particularly in off-road use.
As a result of the above dimensional
differences, Sport utility vehicles and trucks
often have a higher center of gravity and a
greater difference in center of gravity
between the loaded and unloaded condition.
These differences that make your vehicle so
versatile also make it handle differently than
an ordinary passenger car. TIRE CARE
Information About Uniform Tire Quality
Grading
Tire Quality Grades apply to new
pneumatic passenger car tires. The
Quality grades can be found where
applicable on the tire sidewall between
tread shoulder and maximum section
width. For example: Treadwear 200
Traction AA Temperature A. These Tire Quality Grades are
determined by standards that the United
States Department of Transportation has
set.
Tire Quality Grades apply to new
pneumatic passenger car tires. They do
not apply to deep tread, winter-type
snow tires, space-saver or temporary
use spare tires, light truck or LT type
tires, tires with nominal rim diameters of
10 to 12 inches or limited production tires
as defined in Title 49 Code of Federal
Regulations Part 575.104 (c)(2).
U.S. Department of Transportation Tire
quality grades: The U.S. Department of
Transportation requires us to give you
the following information about tire
grades exactly as the government has
written it.
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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 would
wear one and one-half (1 ½) 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
WARNING: The traction grade
assigned to this tire is based on
straight-ahead braking traction tests,
and does not include acceleration,
cornering, hydroplaning or peak
traction characteristics. The traction grades, from highest to
lowest are AA, A, B, and C. The grades
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 WARNING:
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.
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. 139. Grades B and A represent
higher levels of performance on the
laboratory test wheel than the minimum
required by law.
Glossary of Tire Terminology
*
Tire label: A label showing the original
equipment tire sizes, recommended
inflation pressure and the maximum
weight the vehicle can carry.
*
Tire Identification Number (TIN): A
number on the sidewall of each tire
providing information about the tire
brand and manufacturing plant, tire size
and date of manufacture. Also referred
to as DOT code.
*
Inflation pressure: A measure of the
amount of air in a tire.
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*Standard load: A class of P-metric or
Metric tires designed to carry a
maximum load at set pressure. For
example: For P-Metric tires
35 psi
(2.4 bar) and for Metric 36 psi (2.5 bar).
Increasing the inflation pressure beyond
this pressure will not increase the tire ’s
load carrying capability.
*
Extra load: A class of P-metric or Metric
tires designed to carry a heavier
maximum load at
42 psi (2.9 bar).
Increasing the inflation pressure beyond
this pressure will not increase the tire ’s
load carrying capability.
*
kPa: Kilopascal, a metric unit of air
pressure.
*PSI: Pounds per square inch, a standard
unit of air pressure.
*
Cold tire pressure: The tire pressure
when the vehicle has been stationary
and out of direct sunlight for an hour or
more and prior to the vehicle being
driven for 1 mile (1.6 kilometers). *
Recommended inflation pressure: The
cold inflation pressure found on the
Safety Compliance Certification Label
(affixed to either the door hinge pillar,
door-latch post, or the door edge that
meets the door-latch post, next to the
driver's seating position), or Tire Label
located on the B-pillar or the edge of the
driver's door.
B-pillar:
The structural member at the
side of the vehicle behind the front door.
*
Bead area of the tire: Area of the tire
next to the rim.
*
Sidewall of the tire: Area between the
bead area and the tread.
*
Tread area of the tire: Area of the
perimeter of the tire that contacts the
road when mounted on the vehicle.
*
Rim: The metal support (wheel) for a
tire or a tire and tube assembly upon
which the tire beads are seated. Information Contained on the Tire
Sidewall
Both United States and Canada Federal
regulations require tire manufacturers
to place standardized information on the
sidewall of all tires. This information
identifies and describes the fundamental
characteristics of the tire and also
provides a U.S. DOT Tire Identification
Number for safety standard certification
and in case of a recall.
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Information on P Type Tires
P215/65R15 95H is an example of a tire
size, load index and speed rating. The
definitions of these items are listed
below. (Note that the tire size, load index
and speed rating for your vehicle may
be different from this example.) A. P: Indicates a tire, designated by the
Tire and Rim Association, that may be
used for service on cars, sport utility
vehicles, minivans and light trucks.
Note:
If your tire size does not begin with a
letter this may mean it is designated by
either the European Tire and Rim
Technical Organization or the Japan Tire
Manufacturing Association.
B.
215: Indicates the nominal width of
the tire in millimeters from sidewall edge
to sidewall edge. In general, the larger
the number, the wider the tire.
C.
65: Indicates the aspect ratio which
gives the tire's ratio of height to width.
D.
R: Indicates a radial type tire.
E.
15: Indicates the wheel or rim
diameter in inches. If you change your
wheel size, you will have to purchase
new tires to match the new wheel
diameter. F.
95: Indicates the tire's load index. It
is an index that relates to how much
weight a tire can carry. You may find this
information in your owner’ s manual. If
not, contact a local tire dealer.
Note: You may not find this information
on all tires because it is not required by
federal law.
G.
H: Indicates the tire's speed rating.
The speed rating denotes the speed at
which a tire is designed to be driven for
extended periods of time under a
standard condition of load and inflation
pressure. The tires on your vehicle may
operate at different conditions for load
and inflation pressure. These speed
ratings may need to be adjusted for the
difference in conditions. The ratings
range from
81 mph (130 km/h) to
186 mph (299 km/h). These ratings are
listed in the following chart.
Note: You may not find this information
on all tires because it is not required by
federal law.
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mph ( km/h)
Letter rating
81 (130)
M
87 (140)
N
99 (159)
Q
106 (171)
R
112 (180)
S
118 (190)
T
124 (200)
U
130 (210)
H
149 (240)
V mph ( km/h)
Letter rating
168 (270)
W
186 (299)
Y
Note: For tires with a maximum speed
capability over 149 mph (240 km/h), tire
manufacturers sometimes use the letters
ZR. For those with a maximum speed
capability over 186 mph (299 km/h), tire
manufacturers always use the letters
ZR.
H. U.S. DOT Tire Identification Number:
This begins with the letters DOT and
indicates that the tire meets all federal
standards. The next two numbers or
letters are the plant code designating
where it was manufactured, the next two
are the tire size code and the last four
numbers represent the week and year
the tire was built. For example, the
numbers 317 mean the 31st week of
1997. After 2000 the numbers go to four digits. For example, 2501 means the
25th week of 2001. The numbers in
between are identification codes used
for traceability. This information is used
to contact customers if a tire defect
requires a recall.
I.
M+S or M/S: Mud and Snow, or
AT:
All Terrain, or
AS:
All Season.
J.
Tire Ply Composition and Material
Used: Indicates the number of plies or
the number of layers of rubber-coated
fabric in the tire tread and sidewall. Tire
manufacturers also must indicate the ply
materials in the tire and the sidewall,
which include steel, nylon, polyester,
and others.
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K. Maximum Load: Indicates the
maximum load in kilograms and pounds
that can be carried by the tire (affixed to
either the door hinge pillar, door-latch
post, or the door edge that meets the
door-latch post, next to the driver's
seating position), or Tire Label located
on the B-pillar or the edge of the driver's
door.
L.
Treadwear, Traction and
Temperature Grades:
*
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 would wear 1½ times
as well on the government course as a
tire graded 100. *
Traction: The traction grades, from
highest to lowest are AA, A, B, and C.
The grades 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: 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.
M.
Maximum Inflation Pressure:
Indicates the tire manufacturers'
maximum permissible pressure or the
pressure at which the maximum load
can be carried by the tire. This pressure
is normally higher than the vehicle
manufacturer's recommended cold
inflation pressure which can be found
on the Safety Compliance Certification
Label (affixed to either the door hinge
pillar, door-latch post, or the door edge
that meets the door-latch post, next to the driver's seating position), or Tire
Label located on the B-pillar or the edge
of the driver's door. The cold inflation
pressure should never be set lower than
the recommended pressure on the
vehicle label.
The tire suppliers may have additional
markings, notes or warnings such as
standard load or radial tubeless.
Additional Information Contained on
the Tire Sidewall for LT Type Tires
Note:
Tire Quality Grades do not apply
to this type of tire.
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LT type tires have some additional
information beyond those of P type tires.
These differences are described below.
A. LT: Indicates a tire, designated by the
Tire and Rim Association, that is
intended for service on light trucks. B. Load Range and Load Inflation
Limits: Indicates the tire's load-carrying
capabilities and its inflation limits.
C.
Maximum Load Dual lb (kg) at psi
(kPa) cold: Indicates the maximum load
and tire pressure when the tire is used
as a dual; defined as four tires on the
rear axle (a total of six or more tires on
the vehicle).
D.
Maximum Load Single lb (kg) at psi
(kPa) cold: Indicates the maximum load
and tire pressure when the tire is used
as a single; defined as two tires (total)
on the rear axle.
Information on T Type Tires
T145/80D16 is an example of a tire size.
Note: The temporary tire size for your
vehicle may be different from this
example. Tire Quality Grades do not
apply to this type of tire. T type tires have some additional
information beyond those of P type tires.
These differences are described below:
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A. T: Indicates a type of tire, designated
by the Tire and Rim Association, that is
intended for temporary service on cars,
sport utility vehicles, minivans and light
trucks.
B.
145: Indicates the nominal width of
the tire in millimeters from sidewall edge
to sidewall edge. In general, the larger
the number, the wider the tire.
C.
80: Indicates the aspect ratio which
gives the tire's ratio of height to width.
Numbers of 70 or lower indicate a short
sidewall.
D.
D: Indicates a diagonal type tire.
R:
Indicates a radial type tire.
E.
16: Indicates the wheel or rim
diameter in inches. If you change your
wheel size, you will have to purchase
new tires to match the new wheel
diameter. Location of the Tire Label
You will find a Tire Label containing tire
inflation pressure by tire size and other
important information located on the
B-Pillar or the edge of the driver's door.
See
Load Carrying (page 301).
Inflating Your Tires
Safe operation of your vehicle requires
that your tires are properly inflated.
Remember that a tire can lose up to half
of its air pressure without appearing flat.
Every day before you drive, check your
tires. If one looks lower than the others,
use a tire gauge to check pressure of all
tires and adjust if required.
At least once a month and before long
trips, inspect each tire and check the tire
pressure with a tire gauge (including
spare, if equipped). Inflate all tires to the
inflation pressure recommended by us. You are strongly urged to buy a reliable
tire pressure gauge, as automatic
service station gauges may be
inaccurate. We recommend the use of
a digital or dial-type tire pressure gauge
rather than a stick-type tire pressure
gauge.
Use the recommended cold inflation
pressure for optimum tire performance
and wear. Under-inflation or
over-inflation may cause uneven
treadwear patterns.
WARNING: Under-inflation is the
most common cause of tire failures
and may result in severe tire cracking,
tread separation or blowout, with
unexpected loss of vehicle control and
increased risk of injury. Under-inflation
increases sidewall flexing and rolling
resistance, resulting in heat buildup
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