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TIRES
Tires are designed to give many thousands of miles of service, but they
must be maintained in order to get the maximum benefit from them.
Glossary of tire terminology
•Tire label:A label showing the OE (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.
•Standard load:A class of P-metric or Metric tires designed to carry a
maximum load at 35 psi [37 psi (2.5 bar) for Metric tires]. 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 41 psi [43 psi (2.9 bar) for Metric tires].
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 inflation 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 km).
•Recommended inflation pressure:The cold inflation pressure found
on the Safety Compliance Certification Label 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.
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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.)
1.P:Indicates a tire, designated by
the Tire and Rim Association
(T&RA), that may be used for
service on cars, SUVs, minivans and
light trucks.
Note:If your tire size does not
begin with a letter this may mean it
is designated by either ETRTO
(European Tire and Rim Technical Organization) or JATMA (Japan Tire
Manufacturing Association).
2.215: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.
3.65:Indicates the aspect ratio which gives the tire’s ratio of height to
width.
4.R:Indicates a “radial” type tire.
5.15: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.
6.95: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 guide. 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.
7.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.
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Follow these guidelines when using snow tires and chains:
•If possible, avoid fully loading your vehicle.
•Use only SAE Class S chains.
•Install chains securely, verifying that the chains do not touch any
wiring, brake lines or fuel lines.
•Drive cautiously. If you hear the chains rub or bang against your
vehicle, stop and retighten the chains. If this does not work, remove
the chains to prevent damage to your vehicle.
•Remove the tire chains when they are no longer needed. Do not use
tire chains on dry roads.
VEHICLE LOADING – WITH AND WITHOUT A TRAILER
This section will guide you in the proper loading of your vehicle and/or
trailer, to keep your loaded vehicle weight within its design rating
capability, with or without a trailer. Properly loading your vehicle will
provide maximum return of vehicle design performance. Before loading
your vehicle, familiarize yourself with the following terms for determining
your vehicle’s weight ratings, with or without a trailer, from the vehicle’s
Tire Label or Safety Compliance Certification Label:
Base Curb Weight– is the weight of the vehicle including a full tank of
fuel and all standard equipment. It does not include passengers, cargo, or
optional equipment.
Vehicle Curb Weight– is the weight of your new vehicle when you
picked it up from your authorized dealer plus any aftermarket
equipment.
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Payload– is the combined weight of cargo and passengers that the
vehicle is carrying. The maximum payload for your vehicle can be found
on the Tire Label on the B-Pillar or the edge of the driver’s door
(vehicles exported outside the US and Canada may not have a Tire
Label). Look for“THE COMBINED WEIGHT OF OCCUPANTS AND
CARGO SHOULD NEVER EXCEED XXX kg OR XXX lb.”for
maximum payload. The payload listed on the Tire Label is the maximum
payload for the vehicle as built by the assembly plant. If any aftermarket
or authorized-dealer installed equipment has been installed on the
vehicle, the weight of the equipment must be subtracted from the
payload listed on the Tire Label in order to determine the new payload.
WARNING:The appropriate loading capacity of your vehicle can
be limited either by volume capacity (how much space is
available) or by payload capacity (how much weight the vehicle should
carry). Once you have reached the maximum payload of your vehicle,
do not add more cargo, even if there is space available. Overloading or
improperly loading your vehicle can contribute to loss of vehicle
control and vehicle rollover.
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Example only:
Cargo Weight– includes all weight added to the Base Curb Weight,
including cargo and optional equipment. When towing, trailer tongue load
or king pin weight is also part of cargo weight.
GAW (Gross Axle Weight)– is the total weight placed on each axle
(front and rear) – including vehicle curb weight and all payload.
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GAWR (Gross Axle Weight Rating)– is the maximum allowable
weight that can be carried by a single axle (front or rear).These
numbers are shown on the Safety Compliance Certification Label
located on the B-Pillar or the edge of the driver’s door. The total
load on each axle must never exceed its GAWR.
Note:For trailer towing information refer toTrailer towingfound in
this chapter or theRV and Trailer Towing Guideprovided by your
authorized dealer.
GVW (Gross Vehicle Weight)– is the Vehicle Curb Weight + cargo +
passengers.
GVWR (Gross Vehicle Weight Rating)– is the maximum allowable
weight of the fully loaded vehicle (including all options, equipment,
passengers and cargo).The GVWR is shown on the Safety
Compliance Certification Label located on the B-Pillar or the
edge of the driver’s door. The GVW must never exceed the GVWR.
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•Example only:
WARNING:Exceeding the Safety Compliance Certification Label
vehicle weight rating limits could result in substandard vehicle
handling or performance, engine, transmission and/or structural
damage, serious damage to the vehicle, loss of control and personal
injury.
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GCW (Gross Combined Weight)– is the weight of the loaded vehicle
(GVW) plus the weight of the fully loaded trailer.
GCWR (Gross Combined Weight Rating)– is the maximum allowable
weight of the vehicle and the loaded trailer – including all cargo and
passengers – that the vehicle can handle without risking damage.
(Important: The towing vehicle’s braking system is rated for operation at
GVWR, not at GCWR.) Separate functional brakes should be used for
safe control of towed vehicles and for trailers where the GCW of the
towing vehicle plus the trailer exceed the GVWR of the towing vehicle.
The GCW must never exceed the GCWR.
Maximum Loaded Trailer Weight– is the highest possible weight of a
fully loaded trailer the vehicle can tow. It assumes a vehicle with only
mandatory options, no cargo (internal or external), a tongue load of
10–15% (conventional trailer) or king pin weight of 15–25% (fifth wheel
trailer), and driver only (150 lb. [68 kg]).Consult your authorized
dealer (or theRV and Trailer Towing Guideprovided by your
authorized dealer) for more detailed information.
Tongue Load or Fifth Wheel King Pin Weight– refers to the amount
of the weight that a trailer pushes down on a trailer hitch.
Examples:For a 5,000 lb. (2,268 kg) conventional trailer, multiply 5,000
by 0.10 and 0.15 to obtain a proper tongue load range of 500 to 750 lb.
(227 to 340 kg). For an 11,500 lb. (5,216 kg) fifth wheel trailer, multiply
by 0.15 and 0.25 to obtain a proper king pin load range of 1,725 to
2,875 lb. (782 to 1,304 kg)
WARNING:Do not exceed the GVWR or the GAWR specified on
the Safety Compliance Certification Label.
WARNING:Do not use replacement tires with lower load
carrying capacities than the original tires because they may
lower the vehicle’s GVWR and GAWR limitations. Replacement tires
with a higher limit than the original tires do not increase the GVWR
and GAWR limitations.
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