Page 367 of 536

Feedback To The Driver
The instrument cluster has an HDC icon and the HDC
switch has an LED which offer feedback to the driver about
the state HDC is in.
• The cluster icon and switch lamp will illuminate and
remain on solid when HDC is enabled or activated. This
is the normal operating condition for HDC.
• The cluster icon and switch lamp will flash for several
seconds then extinguish when the driver pushes the
HDC switch but enable conditions are not met.
• The cluster icon and switch lamp will flash for several
seconds then extinguish when HDC disables due to
excess speed.
• The cluster icon and switch lamp will flash when HDC
deactivates due to overheated brakes. The flashing will
stop and HDC will activate again once the brakes have
cooled sufficiently.
WARNING!HDC is only intended to assist the driver in controlling
vehicle speed when descending hills. The driver must
remain attentive to the driving conditions and is re-
sponsible for maintaining a safe vehicle speed. TIRE SAFETY INFORMATION
Tire Markings
1 — U.S. DOT Safety Standards
Code (TIN) 4 — Maximum Load
2 — Size Designation 5 — Maximum Pressure
3 — Service Description 6 — Treadwear, Traction and
Temperature Grades 5STARTING AND OPERATING 365
Page 373 of 536
Tire Loading And Tire Pressure
Tire And Loading Information Placard Location
NOTE: The proper cold tire inflation pressure is listed on
the driver ’s side B-Pillar or the rear edge of the driver’s
side door.
Check the inflation pressure of each tire, including the
spare tire (if equipped), at least monthly and inflate to the
recommended pressure for your vehicle.
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.
• Improperly inflated tires are dangerous and can
cause collisions. Under-inflation increases tire flex-
ing and can result in over-heating and tire failure. (Continued)Example Tire Placard Location (Door) Example Tire Placard Location (B-Pillar) 5STARTING AND OPERATING 371
Page 377 of 536
WARNING!Overloading of your tires is dangerous. Overloading
can cause tire failure, affect vehicle handling, and
increase your stopping distance. Use tires of the rec-
ommended load capacity for your vehicle. Never over-
load them. 5STARTING AND OPERATING 375
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Limited Use Spare — If Equipped
The limited use spare tire is for temporary emergency use
only. This tire is identified by a label located on the limited
use spare wheel. This label contains the driving limitations
for this spare. This tire may look like the original equipped
tire on the front or rear axle of your vehicle, but it is not.
Installation of this limited use spare tire affects vehicle
handling. Since it is not the same as your original equip-
ment tire, replace (or repair) the original equipment tire
and reinstall on the vehicle at the first opportunity.
WARNING!Limited use spares are for emergency use only. Instal-
lation of this limited use spare tire affects vehicle
handling. With this tire, do not drive more than the
speed listed on the limit use spare wheel. Keep in-
flated to the cold tire inflation pressures listed on your
Tire and Loading Information Placard located on the
driver ’s side B-Pillar or the rear edge of the driver ’s
side door. Replace (or repair) the original equipment
tire at the first opportunity and reinstall it on your
vehicle. Failure to do so could result in loss of vehicle
control. Tire Spinning
When stuck in mud, sand, snow, or ice conditions, do not
spin your vehicle’s wheels above 30 mph (48 km/h) or for
longer than 30 seconds continuously without stopping.
Refer to “Freeing A Stuck Vehicle” in “What To Do In
Emergencies” for further information.
WARNING!Fast spinning tires can be dangerous. Forces generated
by excessive wheel speeds may cause tire damage or
failure. A tire could explode and injure someone. Do
not spin your vehicle’s wheels faster than 30 mph
(48 km/h) for more than 30 seconds continuously when
you are stuck, and do not let anyone near a spinning
wheel, no matter what the speed.382 STARTING AND OPERATING
Page 388 of 536

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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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
Page 394 of 536

NOTE:
• The TPMS is not intended to replace normal tire care and
maintenance or to provide warning of a tire failure or
condition.
• The TPMS should not be used as a tire pressure gauge
while adjusting your tire pressure.
• Driving on a significantly under-inflated tire causes the
tire to overheat and can lead to tire failure. Under-
inflation also reduces fuel efficiency and tire tread life,
and may affect the vehicle’s handling and stopping
ability.
• The TPMS is not a substitute for proper tire mainte-
nance, and it is the driver ’s responsibility to maintain
correct tire pressure using an accurate tire pressure
gauge, even if under-inflation has not reached the level
to trigger illumination of the “Tire Pressure Monitoring
Telltale Light.”
• Seasonal temperature changes will affect tire pressure,
and the TPMS will monitor the actual tire pressure in the
tire. Base System — If Equipped
The Tire Pressure Monitor System (TPMS) uses wireless
technology with wheel rim mounted electronic sensors to
monitor tire pressure levels. Sensors mounted to each
wheel as part of the valve stem transmit tire pressure
readings to the receiver module.
NOTE: It is particularly important for you to check the tire
pressure in all of the tires on your vehicle monthly and to
maintain the proper pressure.
The TPMS consists of the following components:
• Receiver module
• Four TPM sensors
• TPM Telltale Light
The matching full size spare wheel and tire assembly (if
equipped) has a TPM sensor. The matching full size spare
can be used in place of any of the four road tires. The TPMS
will only monitor the pressure in the full size spare when
it is used in place of a road tire. Otherwise, a spare with a
pressure below the low-pressure limit will not cause the
“Tire Pressure Monitoring Telltale Light” to illuminate or
the chime to sound.392 STARTING AND OPERATING