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Tread Wear Indicators
Tread wear indicators are in the original equipment tires to
help you in determining when your tires should be re-
placed. These indicators are molded into the bottom of the tread
grooves. They will appear as bands when the tread depth
becomes a 1/16 of an inch (1.6 mm). When the tread is
worn to the tread wear indicators, the tire should be
replaced. Refer to “Replacement Tires” in this section for
further information.
Life Of Tire
The service life of a tire is dependent upon varying factors
including, but not limited to:
• Driving style.
• Tire pressure – Improper cold tire inflation pressures can
cause uneven wear patterns to develop across the tire
tread. These abnormal wear patterns will reduce tread
life, resulting in the need for earlier tire replacement.
• Distance driven.
• Performance tires, tires with a speed rating of V or
higher, and Summer tires typically have a reduced tread
life. Rotation of these tires per the vehicle maintenance
schedule is highly recommended.Tire Tread1—WornTire
2—NewTire 5STARTING AND OPERATING 383
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WARNING!Tires and the spare tire should be replaced after six
years, regardless of the remaining tread. Failure to
follow this warning can result in sudden tire failure.
You could lose control and have a collision resulting in
serious injury or death.
Keep dismounted tires in a cool, dry place with as little
exposure to light as possible. Protect tires from contact with
oil, grease, and gasoline.
Replacement Tires
The tires on your new vehicle provide a balance of many
characteristics. They should be inspected regularly for
wear and correct cold tire inflation pressures. The manu-
facturer strongly recommends that you use tires equivalent
to the originals in size, quality and performance when
replacement is needed. Refer to the paragraph on “Tread
Wear Indicator” in this section. Refer to the Tire and
Loading Information placard or the Vehicle Certification
Label for the size designation of your tire. The Load Index
and Speed Symbol for your tire will be found on the
original equipment tire sidewall. See the Tire Sizing Chart example found in the “Tire Safety
Information” section of this manual for more information
relating to the Load Index and Speed Symbol of a tire.
It is recommended to replace the two front tires or two rear
tires as a pair. Replacing just one tire can seriously affect
your vehicle’s handling. If you ever replace a wheel, make
sure that the wheel’s specifications match those of the
original wheels.
It is recommended you contact your authorized tire dealer
or original equipment dealer with any questions you may
have on tire specifications or capability. Failure to use
equivalent replacement tires may adversely affect the
safety, handling, and ride of your vehicle.384 STARTING AND OPERATING
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WARNING!• Do not use a tire, wheel size or rating other than that
specified for your vehicle. Some combinations of
unapproved tires and wheels may change suspen-
sion dimensions and performance characteristics,
resulting in changes to steering, handling, and brak-
ing of your vehicle. This can cause unpredictable
handling and stress to steering and suspension com-
ponents. You could lose control and have a collision
resulting in serious injury or death. Use only the tire
and wheel sizes with load ratings approved for your
vehicle.
• 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.
• Failure to equip your vehicle with tires having ad-
equate speed capability can result in sudden tire
failure and loss of vehicle control. CAUTION!Replacing original tires with tires of a different size
may result in false speedometer and odometer read-
ings.
TIRE CHAINS (TRACTION DEVICES)
Use of traction devices require sufficient tire-to-body clear-
ance. Follow these recommendations to guard against
damage.
• Traction device must be of proper size for the tire, as
recommended by the traction device manufacturer. 5STARTING AND OPERATING 385
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Please follow the table below for proper tire size, chain
type, and axle recommendations:
Vehicle Axle
Recommenda-
tions Tire Sizes Chain Class
Chassis Cab 3500 (Single Rear Wheel) Models Rear Only LT265/70R18E U Class
Chassis Cab 3500 (Dual Rear Wheel) 4X2 Models Rear Only LT235/80R17E U Class
Chassis Cab 3500 (Dual Rear Wheel) 4X4 Models Front/Rear LT235/80R17E U Class
Chassis Cab 4500/5500 Models Rear Only 225/70R19.5G U Class
WARNING!Using tires of different size and type (M+S, Snow)
between front and rear axles can cause unpredictable
handling. You could lose control and have a collision.
CAUTION!To avoid damage to your vehicle or tires, observe the
following precautions:
• Because of restricted traction device clearance be-
tween tires and other suspension components, it is (Continued) CAUTION! (Continued)important that only traction devices in good condi-
tion are used. Broken devices can cause serious
damage. Stop the vehicle immediately if noise occurs
that could indicate device breakage. Remove the
damaged parts of the device before further use.
• Install device as tightly as possible and then re-
tighten after driving about ½ mile (0.8 km).
• Do not exceed 30 mph (48 km/h).
• Drive cautiously and avoid severe turns and large
bumps, especially with a loaded vehicle. (Continued)386 STARTING AND OPERATING
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CAUTION! (Continued)• Do not drive for a prolonged period on dry pave-
ment.
• Observe the traction device manufacturer ’s instruc-
tions on the method of installation, operating speed,
and conditions for use. Always use the suggested
operating speed of the device manufacturer ’s if it is
less than 30 mph (48 km/h).
• Do not use traction devices on a compact spare tire.
TIRE ROTATION RECOMMENDATIONS
Tires on the front and rear axles of vehicles operate at
different loads and perform different steering, driving, and
braking functions. For these reasons, they wear at unequal
rates.
These effects can be reduced by timely rotation of tires. The
benefits of rotation are especially worthwhile with aggres-
sive tread designs such as those on On/Off Road type tires.
Rotation will increase tread life, help to maintain mud,
snow, and wet traction levels, and contribute to a smooth,
quiet ride. Refer to the “Maintenance Schedule” for the proper main-
tenance intervals. More frequent rotation is permissible if
desired. The reasons for any rapid or unusual wear should
be corrected prior to rotation being performed.
NOTE: On Canadian vehicles only, if your vehicle is
equipped with All-Season type tires on the front and
On/Off Road type tires mounted on the rear, do not use a
front to back rotation pattern. Instead, rotate your tires side
to side at the recommended intervals. Tire Rotation 5STARTING AND OPERATING 387
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Dual Rear Wheels
The tires used on dual wheel assemblies should be
matched for wear to prevent overloading one tire in a set.
To check if tires are even, lay a straight edge across all four
tires. The straight edge should touch all the tires.
NOTE: If your vehicle is equipped with a Tire Pressure
Information System (TPIS):
• The Tire Pressure Information System (TPIS) uses
unique sensors in the inner rear wheels to help identify them from the outer rear wheels, because of this, the
inner and outer wheel locations can’t be switched.
• After a tire rotation is completed, as shown below, the
system can auto learn the locations of each sensor ID.
Auto learning/localization occurs when the vehicle ig-
nition status is changed from Off to On and speeds of
greater than 5 mph (8km/h) are obtained and remain
over 5mph (8km/h) for at about a 15 minute period. You
may need to drive for 20 minutes to account slower
speeds and stops.
• If the tires are rotated incorrectly, the Auto localization of
the TPIS sensors will fail to locate correctly resulting in
incorrect locations for the pressure values displayed in
the Instrument Cluster.
CAUTION!• 4500/5500 Dual Rear Tires may only have one ap-
proved direction of rotation. This is to accommodate
the asymmetrical design (tread pattern) of the On/
Off road tire. (Continued)Tire Rotation388 STARTING AND OPERATING
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CAUTION! (Continued)• When replacing a flat, the spare tire may have to be
remounted on the rim or installed at a different
location to maintain the correct placement of the tire
on the wheel relative to the tire/wheel position on
the vehicle. For example, if the spare is used to
replace an outer rear tire it will have to be remounted
on the rim so that the wheel is dished inward. That
way the tread design of asymmetrical tires will
maintain proper position.
DEPARTMENT OF TRANSPORTATION UNIFORM
TIRE QUALITY GRADES
The following tire grading categories were established by
the National Highway Traffic Safety Administration. The
specific grade rating assigned by the tire’s manufacturer in
each category is shown on the sidewall of the tires on your
vehicle.
All passenger vehicle tires must conform to Federal safety
requirements in addition to these grades. Treadwear
The Treadwear grade is a comparative rating, based on the
wear rate of the tire when tested under controlled condi-
tions on a specified government test course. For example, a
tire graded 150 would wear one and one-half 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 Grades
The Traction grades, from highest to lowest, are AA, A, B,
and C. These 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.
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. 5STARTING AND OPERATING 389
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Temperature Grades
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 con-
trolled 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
vehicle 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 established for a
tire that is properly inflated and not overloaded. Ex-
cessive speed, under-inflation, or excessive loading,
either separately or in combination, can cause heat
buildup and possible tire failure. TIRE PRESSURE MONITOR SYSTEM (TPMS)
The Tire Pressure Monitor System (TPMS) will warn the
driver of a low tire pressure based on the vehicle recom-
mended cold placard pressure.
The tire pressure will vary with temperature by about 1 psi
(7 kPa) for every 12°F (6.5°C). This means that when the
outside temperature decreases, the tire pressure will de-
crease. Tire pressure should always be set based on cold
inflation tire pressure. This is defined as the tire pressure
after the vehicle has not been driven for at least three
hours, or driven less than 1 mile (1.6 km) after a three hour
period. The cold tire inflation pressure must not exceed the
maximum inflation pressure molded into the tire sidewall.
Refer to “Tires – General Information” in “Starting And
Operating” for information on how to properly inflate the
vehicle’s tires. The tire pressure will also increase as the
vehicle is driven - this is normal and there should be no
adjustment for this increased pressure.
The TPMS will warn the driver of a low tire pressure if the
tire pressure falls below the low-pressure warning limit for
any reason, including low temperature effects and natural
pressure loss through the tire.390 STARTING AND OPERATING