Tire Terminology And Definitions
Term Definition
B-Pillar The vehicle B-Pillar is the structural member of the body located
behind the front door.
Cold Tire Inflation Pressure Cold tire inflation pressure is defined as the tire pressure after the
vehicle has not been driven for at least 3 hours, or driven less
than 1 mile (1.6 km) after sitting for a three hour period. Inflation
pressure is measured in units of PSI (pounds per square inch) or
kPa (kilopascals).
Maximum Inflation Pressure The maximum inflation pressure is the maximum permissible cold
tire inflation pressure for this tire. The maximum inflation pres-
sure is molded into the sidewall.
Recommended Cold Tire Inflation
Pressure Vehicle manufacturer’s recommended cold tire inflation pressure
as shown on the tire placard.
Tire Placard A paper label permanently attached to the vehicle describing the
vehicle’s loading capacity, the original equipment tire sizes and
the recommended cold tire inflation pressures.
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This placard tells you important information about
the:
1) number of people that can be carried in the vehicle
2) total weight your vehicle can carry
3) tire size designed for your vehicle
4) cold tire inflation pressures for the front, rear, and
spare tires.
Loading
The vehicle maximum load on the tire must not exceed
the load carrying capacity of the tire on your vehicle. You
will not exceed the tire’s load carrying capacity if you
adhere to the loading conditions, tire size, and cold tire
inflation pressures specified on the Tire and Loading
Information placard and in the “Vehicle Loading” section
of this manual.
NOTE: Under a maximum loaded vehicle condition,
gross axle weight ratings (GAWRs) for the front and rear axles must not be exceeded. For further information on
GAWRs, vehicle loading, and trailer towing, refer to
“Vehicle Loading” in this section.
To determine the maximum loading conditions of your
vehicle, locate the statement “The combined weight of
occupants and cargo should never exceed XXX lbs or
XXX kg” on the Tire and Loading Information placard.
The combined weight of occupants, cargo/luggage and
trailer tongue weight (if applicable) should never exceed
the weight referenced here.
Steps For Determining Correct Load Limit
1. Locate the statement “The combined weight of occu-
pants and cargo should never exceed XXX lbs or XXX kg”
on your vehicle’s placard.
2. Determine the combined weight of the driver and
passengers that will be riding in your vehicle.
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3. Subtract the combined weight of the driver and pas-
sengers from XXX lbs or XXX kg.
4. The resulting figure equals the available amount of
cargo and luggage load capacity. For example, if “XXX”
amount equals 1,400 lbs (635 kg) and there will be five
150 lb (68 kg) passengers in your vehicle, the amount of
available cargo and luggage load capacity is 650 lbs
(295 kg) (since 5 x 150 = 750, and 1400 – 750 = 650 lbs
[295 kg]).
5. Determine the combined weight of luggage and cargo
being loaded on the vehicle. That weight may not safely
exceed the available cargo and luggage load capacity
calculated in Step 4.
6. If your vehicle will be towing a trailer, load from your
trailer will be transferred to your vehicle. Consult this
manual to determine how this reduces the available
cargo and luggage load capacity of your vehicle. NOTE:
• The following table shows examples on how to calcu-
late total load, cargo/luggage, and towing capacities
of your vehicle with varying seating configurations
and number and size of occupants. This table is for
illustration purposes only and may not be accurate for
the seating and load carry capacity of your vehicle.
• For the following example, the combined weight of
occupants and cargo should never exceed 865 lbs
(392 kg).316 STARTING AND OPERATING
WARNING!Overloading of your tires is dangerous. Overloading
can cause tire failure, affect vehicle handling, and
increase your stopping distance. Use tires of the
recommended load capacity for your vehicle. Never
overload them.
TIRES — GENERAL INFORMATION
Tire Pressure
Proper tire inflation pressure is essential to the safe and
satisfactory operation of your vehicle. Three primary
areas are affected by improper tire pressure: Safety
WARNING!• Improperly inflated tires are dangerous and can
cause collisions.
• Under-inflation increases tire flexing and can re-
sult in tire failure.
• Over-inflation reduces a tire’s ability to cushion
shock. Objects on the road and chuckholes can
cause damage that result in tire failure.
• Over-inflated or under-inflated tires can affect
vehicle handling and can fail suddenly, resulting
in loss of vehicle control.
• Unequal tire pressures can cause steering prob-
lems. You could lose control of your vehicle.
(Continued)318 STARTING AND OPERATING
WARNING! (Continued)• Never use a tire with a smaller load index or
capacity, other than what was originally equipped
on your vehicle. Using a tire with a smaller load
index could result in tire overloading and failure.
You could lose control and have a collision result-
ing in serious injury or death.
• Failure to equip your vehicle with tires having
adequate speed capability can result in sudden tire
failure and loss of vehicle control resulting in
serious injury or death.
CAUTION!Replacing original tires with tires of a different size
may result in false speedometer and odometer read-
ings. SUPPLEMENTAL TIRE PRESSURE INFORMATION
— IF EQUIPPED
A light load vehicle condition is defined as two passen-
gers [150 lbs (68 kg) each] plus 200 lbs (91 kg) of cargo.
Cold tire inflation pressures for a lightly loaded vehicle
will be found on the face of the driver’s door.
TIRE CHAINS
Use “Class U” chains or other traction aids that meet SAE
Type “U” specifications.
NOTE: Chains must be the proper size for the vehicle,
as recommended by the chain manufacturer.
CAUTION!To avoid damage to your vehicle, tires or chains,
observe the following precautions:
(Continued)330 STARTING AND OPERATING
VEHICLE LOADING
Certification Label
As required by National Highway Traffic Safety Admin-
istration regulations, your vehicle has a certification label
affixed to the driver’s side door or pillar.
This label contains the month and year of manufacture,
Gross Vehicle Weight Rating (GVWR), Gross Axle Weight
Rating (GAWR) front and rear, and Vehicle Identification
Number (VIN). A Month-Day-Hour (MDH) number is
included on this label and indicates the Month, Day and
Hour of manufacture. The bar code that appears on the
bottom of the label is your Vehicle Identification Number
(VIN).
Gross Vehicle Weight Rating (GVWR)
The GVWR is the total permissible weight of your vehicle
including driver, passengers, vehicle, options and cargo.
The label also specifies maximum capacities of front and rear axle systems (GAWR). Total load must be limited so
GVWR and front and rear GAWR are not exceeded.
Payload
The payload of a vehicle is defined as the allowable load
weight a truck can carry, including the weight of the
driver, all passengers, options and cargo.
Gross Axle Weight Rating (GAWR)
The GAWR is the maximum permissible load on the front
and rear axles. The load must be distributed in the cargo
area so that the GAWR of each axle is not exceeded.
Each axle GAWR is determined by the components in the
system with the lowest load carrying capacity (axle,
springs, tires or wheels). Heavier axles or suspension
components sometimes specified by purchasers for in-
creased durability does not necessarily increase the vehi-
cle’s GVWR.342 STARTING AND OPERATING
Tire Size
The tire size on the Label represents the actual tire size on
your vehicle. Replacement tires must be equal to the load
capacity of this tire size.
Rim Size
This is the rim size that is appropriate for the tire size
listed.
Inflation Pressure
This is the cold tire inflation pressure for your vehicle for
all loading conditions up to full GAWR.
Curb Weight
The curb weight of a vehicle is defined as the total weight
of the vehicle with all fluids, including vehicle fuel, at full
capacity conditions, and with no occupants or cargo
loaded into the vehicle. The front and rear curb weight
values are determined by weighing your vehicle on a
commercial scale before any occupants or cargo are
added. Loading
The actual total weight and the weight of the front and
rear of your vehicle at the ground can best be determined
by weighing it when it is loaded and ready for operation.
The entire vehicle should first be weighed on a commer-
cial scale to insure that the GVWR has not been exceeded.
The weight on the front and rear of the vehicle should
then be determined separately to be sure that the load is
properly distributed over front and rear axle. Weighing
the vehicle may show that the GAWR of either the front
or rear axles has been exceeded but the total load is
within the specified GVWR. If so, weight must be shifted
from front to rear or rear to front as appropriate until the
specified weight limitations are met. Store the heavier
items down low and be sure that the weight is distributed
equally. Stow all loose items securely before driving.
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The recommended way to measure GTW is to put your
fully loaded trailer on a vehicle scale. The entire weight
of the trailer must be supported by the scale.
Gross Combination Weight Rating (GCWR)
The GCWR is the total permissible weight of your vehicle
and trailer when weighed in combination.
NOTE: The GCWR rating includes a 150 lbs (68 kg)
allowance for the presence of a driver.
Gross Axle Weight Rating (GAWR)
The GAWR is the maximum capacity of the front and rear
axles. Distribute the load over the front and rear axles
evenly. Make sure that you do not exceed either front or
rear GAWR. Refer to “Vehicle Loading/Vehicle Certifica-
tion Label” in “Starting and Operating” for further
information. WARNING!It is important that you do not exceed the maximum
front or rear GAWR. A dangerous driving condition
can result if either rating is exceeded. You could lose
control of the vehicle and have a collision.
Tongue Weight (TW)
The tongue weight is the downward force exerted on the
hitch ball by the trailer. In most cases it should not be less
than 10% or more than 15% of the trailer load. You must
consider this as part of the load on your vehicle.
Frontal Area
The frontal area is the maximum height multiplied by the
maximum width of the front of a trailer.
Trailer Sway Control
The trailer sway control can be a mechanical telescoping
link that can be installed between the hitch receiver and
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