2021 RAM CHASSIS CAB tire pressure

STARTING AND OPERATING161
The 4H and 4L positions are intended for loose,
slippery road surfaces only. Driving in the 4H
and 4L positions on dry, hard surfaced roads
may cause increased tire wear and damage to
the driveline components.
The “Transfer Case Position Indicator Light” in
the instrument cluster will alert the driver that
the vehicle is in four-wheel drive and that the
front and rear driveshafts are locked together.
This light will illuminate when the transfer case
is shifted into either the 4H or 4L position. There
is no light for the 2H or N (Neutral) positions on
some models.
When operating your vehicle in 4L, the engine
speed is approximately three times that of the
4H or 4L positions at a given road speed. Take
care not to overspeed the engine and do not
exceed 25 mph (40 km/h).
Proper operation of four-wheel drive vehicles
depends on tires of equal size, type and
circumference on each wheel. Any difference
will adversely affect shifting and can cause
damage to the drivetrain. NOTE:
Do not attempt to make a shift while only the
front or rear wheels are spinning, as this can
cause damage to driveline components.
Because four-wheel drive provides improved
traction, there is a tendency to exceed safe
turning and stopping speeds. Do not go faster
than road conditions permit.
NOTE:
Delayed shifts out of four-wheel drive may be
experienced due to uneven tire wear, low or
uneven tire pressures, excessive vehicle
loading, or cold temperatures.Shifting Procedure — Manually Shifted
Transfer Case
2H To 4H
Shifting between 2H and 4H can be made with
the vehicle stopped or in motion. If the vehicle
is in motion, shifts can be made up to 55 mph
(88 km/h). With the vehicle in motion, the
transfer case will engage/disengage faster if
you momentarily release the accelerator pedal
after completing the shift. Apply a constant
force when shifting the transfer case lever.
2WD High Or 4WD High To 4WD Low
NOTE:
When shifting into or out of 4L some gear noise
may be heard. This noise is normal and is not
detrimental to the vehicle or occupants.
With the vehicle rolling at 2 to 3 mph (3 to
5 km/h), shift the transmission into NEUTRAL.
While the vehicle is coasting at 2 to 3 mph (3 to
5 km/h), shift the transfer case lever firmly to
the desired position. Do not pause in transfer
case Neutral.
WARNING!

You or others could be injured or killed if you
leave the vehicle unattended with the transfer
case in the N (NEUTRAL) position without first
fully engaging the parking brake. The transfer
case N (NEUTRAL) position disengages both the
front and rear drive shafts from the powertrain
and will allow the vehicle to roll, even if the
transmission is in PARK. The parking brake
should always be applied when the driver is
not in the vehicle.

4

21_DPF_OM_EN_USC_t.book Page 161

200STARTING AND OPERATING
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 increased
durability does not necessarily increase the
vehicle's GVWR.

TIRE SIZE
The tire size on the Vehicle Certification 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
commercial scale to ensure 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 the front and rear axles.
Weighing the vehicle may show that the GAWR
of either the front or rear axle 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.
Improper weight distributions can have an
adverse effect on the way your vehicle steers
and handles and the way the brakes operate.
TRAILER TOWING
In this section you will find safety tips and
information on limits to the type of towing you
can reasonably do with your vehicle. Before
towing a trailer, carefully review this information
to tow your load as efficiently and safely as
possible.
To maintain the New Vehicle Limited Warranty
coverage, follow the requirements and
recommendations in this manual concerning
vehicles used for trailer towing.
CAUTION!

Do not load your vehicle any heavier than the
GVWR or the maximum front and rear GAWR. If
you do, parts on your vehicle can break, or it
can change the way your vehicle handles.
This could cause you to lose control. Also
overloading can shorten the life of your vehicle.

21_DPF_OM_EN_USC_t.book Page 200

206STARTING AND OPERATING
(Continued)
Towing Requirements — Tires
Do not attempt to tow a trailer while using a
compact spare tire.
Do not drive more than 50 mph (80 km/h) when towing while using a full size spare tire.
Proper tire inflation pressures are essential
to the safe and satisfactory operation of your
vehicle.
Check the trailer tires for proper tire inflation
pressures before trailer usage.
Check for signs of tire wear or visible tire
damage before towing a trailer.
For the proper tire replacement procedures.
Replacing tires with a higher load carrying
capacity will not increase the vehicle's GVWR
and GAWR limits.
For further information Ú page 406.
Towing Requirements — Trailer Brakes
Do not interconnect the hydraulic brake
system or vacuum system of your vehicle
with that of the trailer. This could cause inad -
equate braking and possible personal injury.
An electronically actuated trailer brake
controller is required when towing a trailer
with electronically actuated brakes. When
towing a trailer equipped with a hydraulic
surge actuated brake system, an electronic
brake controller is not required.
Trailer brakes are recommended for trailers
over 1,000 lbs (453 kg) and required for
trailers in excess of 2,000 lbs (907 kg).
WARNING!

Make certain that the load is secured in the
trailer and will not shift during travel. When
trailering cargo that is not fully secured,
dynamic load shifts can occur that may be diffi -
cult for the driver to control. You could lose
control of your vehicle and have a collision.

When hauling cargo or towing a trailer, do
not overload your vehicle or trailer. Over -
loading can cause a loss of control, poor
performance or damage to brakes, axle,
engine, transmission, steering, suspension,
chassis structure or tires.
Safety chains must always be used
between your vehicle and trailer. Always
connect the chains to the hook retainers of
the vehicle hitch. Cross the chains under
the trailer tongue and allow enough slack
for turning corners.
Vehicles with trailers should not be parked
on a grade. When parking, apply the
parking brake on the tow vehicle. Put the
tow vehicle transmission in PARK. For
four-wheel drive vehicles, make sure the
transfer case is not in NEUTRAL. Always,
block or "chock" the trailer wheels.
GCWR must not be exceeded.
Total weight must be distributed between
the tow vehicle and the trailer such that the
following four ratings are not exceeded :
GVWR
GTW
GAWR
Tongue weight rating for the trailer
hitch utilized.
WARNING! (Continued)

21_DPF_OM_EN_USC_t.book Page 206

284SAFETY
TIRE PRESSURE MONITORING
S
YSTEM (TPMS)
(Vehicles Under 10K Gross Vehicle Weight
Rating (GVWR) Only)
The Tire Pressure Monitoring System (TPMS)
will warn the driver of a low tire pressure based
on the vehicle recommended cold placard
pressure.
NOTE:
The TPMS Warning Light will illuminate in the
instrument cluster and a chime will sound when
tire pressure is low in one or more of the four
active road tires. In addition, the instrument
cluster will display a graphic showing the pres -
sure values of each tire with the low tire pres -
sure values in a different color, or the Uconnect
radio will display a TPMS message. When this
occurs you must increase the tire pressure to
the recommended cold placard pressure in
order for the TPMS Warning Light to turn off.
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 decrease.
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. The tire pressure will also
increase as the vehicle is driven — this is normal
and there should be no adjustment for this
increased pressure.
See
Úpage 406 on how to properly inflate the
vehicle’s tires.
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.
The TPMS will continue to warn the driver of low
tire pressure as long as the condition exists,
and will not turn off until the tire pressure is
at or above the recommended cold placard
pressure. Once the low TPMS Warning Light
illuminates, you must increase the tire pressure
to the recommended cold placard pressure in
order for the TPMS Warning Light to turn off.
The system will automatically update and the
TPMS Warning Light will turn off once the
system receives the updated tire pressures. The vehicle may need to be driven for up to
20 minutes above 15 mph (24 km/h) in order
for the TPMS to receive this information.
NOTE:
When filling warm tires, the tire pressure may
need to be increased up to an additional 4 psi
(28 kPa) above the recommended cold placard
pressure in order to turn the TPMS Warning
Light off.

For example, your vehicle may have a
recommended cold (parked for more than
three hours) placard pressure of 30 psi
(207 kPa). If the ambient temperature is 68°F
(20°C) and the measured tire pressure is 27 psi
(186 kPa), a temperature drop to 20°F (-7°C) will
decrease the tire pressure to approximately
23 psi (158 kPa). This tire pressure is sufficiently
low enough to turn on the TPMS Warning Light.
Driving the vehicle may cause the tire pressure to
rise to approximately 27 psi (186 kPa), but the
TPMS Warning Light will still be on. In this
situation, the TPMS Warning Light will turn off
only after the tires are inflated to the vehicle’s
recommended cold placard pressure value

Ú

page 449.

21_DPF_OM_EN_USC_t.book Page 284

SAFETY285
NOTE:
The TPMS is not intended to replace normal
tire care and maintenance or to provide
warning of a tire failure or condition.
If your vehicle is not equipped with the Tire
Fill Alert feature the TPMS should not be used
as a tire pressure gauge while adjusting your
tire pressure.
Driving on a significantly underinflated tire
causes the tire to overheat and can lead to
tire failure. Underinflation 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
maintenance, and it is the driver’s responsi -
bility to maintain correct tire pressure using an
accurate tire pressure gauge, even if underin-
flation has not reached the level to trigger illu -
mination of the TPMS Warning Light.

Seasonal temperature changes will affect
tire pressure, and the TPMS will monitor the
actual tire pressure in the tire.
Example: Tire Pressure Monitoring System Display

The Tire Pressure Monitoring 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.
CAUTION!
The TPMS has been optimized for the orig -
inal equipment tires and wheels. TPMS
pressures and warning have been estab -
lished for the tire size equipped on your
vehicle. Undesirable system operation or
sensor damage may result when using
replacement equipment that is not of the
same size, type, and/or style. Aftermarket
wheels can cause sensor damage.
Using aftermarket tire sealants may cause
the Tire Pressure Monitoring System
(TPMS) sensor to become inoperable.
After using an aftermarket tire sealant it is
recommended that you take your vehicle to
an authorized dealership to have your
sensor function checked.
After inspecting or adjusting the tire pres -
sure always reinstall the valve stem cap.
This will prevent moisture and dirt from
entering the valve stem, which could
damage the TPMS sensor.
6

21_DPF_OM_EN_USC_t.book Page 285

286SAFETY
The TPMS consists of the following
components:
Receiver module
Four Tire Pressure Monitoring System
sensors
Various Tire Pressure Monitoring System
messages, which display in the instrument
cluster

Tire Pressure Monitoring System Warning Light

Tire Pressure Monitoring System Low
Pressure Warnings
The Tire Pressure Monitoring System
Warning Light will illuminate in the
instrument cluster when tire pressure
is low in one or more of the four active
road tires. The instrument cluster will display a
graphic showing the pressure values of each
tire with the low tire pressure values in a
different color. An "Inflate to XX" message will
also be displayed.
Example: Low Tire Pressure Display

Should this occur, you should stop as soon as
possible and inflate the tires with a low pressure
condition (those in a different color in the
instrument cluster graphic) to the vehicle’s
recommended cold placard pressure inflation
value as shown in the "Inflate to XX" message.
Once the system receives the updated tire
pressures, the system will automatically
update, the graphic display in the instrument
cluster will return to its original color, and the
Tire Pressure Monitoring System Warning Light
will turn off. The vehicle may need to be driven
for up to 20 minutes above 15 mph (24 km/h)
in order for the TPMS to receive this
information. NOTE:
When filling warm tires, the tire pressure may
need to be increased up to an additional 4 psi
(28 kPa) above the recommended cold placard
pressure in order to turn the Tire Pressure Moni
-
toring System Warning Light off.
Service TPMS Warning
If a system fault is detected, the Tire Pressure
Monitoring System Warning Light will flash on
and off for 75 seconds and then remain on
solid. In addition, the instrument cluster will
display a "SERVICE TPM SYSTEM" message for
a minimum of five seconds and then display
dashes (- -) in place of the pressure value to
indicate which sensor is not being received.

If the ignition switch is cycled, this sequence will
repeat, providing the system fault still exists.
If the system fault no longer exists, the Tire
Pressure Monitoring System Warning Light will no
longer flash, and the "SERVICE TPM SYSTEM"
message will no longer display, and a pressure

21_DPF_OM_EN_USC_t.book Page 286

SAFETY287

value will display in place of the dashes. A system
fault can occur due to any of the following:

Signal interference due to electronic devices
or driving next to facilities emitting the same
radio frequencies as the TPMS sensors.
Installing aftermarket window tinting that
contains materials that may block radio wave
signals.
Accumulation of snow or ice around the
wheels or wheel housings.
Using tire chains on the vehicle.
Using wheels/tires not equipped with TPMS
sensors.

A system fault may occur due to an incorrect
TPMS sensor location condition. When a system
fault occurs due to an incorrect TPMS sensor
location, the Tire Pressure Monitoring System
Warning Light will flash on and off for 75 seconds
and then remain on solid. The system fault will
also sound a chime. In addition, the instrument
cluster will display a “Tire Pressure Temporarily
Unavailable” message in place of the tire
pressure display screen. If the ignition switch is
cycled, this sequence will repeat, providing the
system fault still exists. If the system fault no longer exists, the Tire Pressure Monitoring
System Indicator Light will no longer flash and the
tire pressure display screen will be displayed
showing the tire pressure values in the correct
locations.

Vehicles With Non-Matching Full Size Spare Or
Compact Spare
The non-matching full size spare or compact
spare tire does not have a TPMS sensor.
Therefore, the TPMS will not monitor the
pressure in the non-matching full size spare
or compact spare tire.
If you install the non-matching full size spare
or compact spare tire in place of a road tire
that has a pressure below the low-pressure
warning limit, upon the next ignition switch
cycle, the TPMS Warning Light and a “LOW
TIRE” message will remain on and a chime
will sound. In addition, the graphic in the
instrument cluster will still display a pressure
value in a different color and an “Inflate to
XX” message.
After driving the vehicle for up to 20 minutes
above 15 mph (24 km/h), the TPMS Warning
Light will flash on and off for 75 seconds and
then remain on solid. In addition, the instru -ment cluster will display a "SERVICE TPM
SYSTEM" message for a minimum of
five seconds and then display dashes (- -) in
place of the pressure value.

For each subsequent ignition switch cycle, a
chime will sound, the TPMS Warning Light will
flash on and off for 75 seconds and then
remain on solid, and the instrument cluster will
display a "SERVICE TPM SYSTEM" message for
a minimum of five seconds and then display
dashes (- -) in place of the pressure value.

Once you repair or replace the original road
tire and reinstall it on the vehicle in place of
the non matching full size spare or compact
spare, the TPMS will update automatically.
In addition, the TPMS Warning Light will turn
off and the graphic in the instrument cluster
will display a new pressure value instead of
dashes (- -), as long as no tire pressure is
below the low-pressure warning limit in any of
the four active road tires. The vehicle may
need to be driven for up to 20 minutes above
15 mph (24 km/h) in order for the TPMS to
receive this information.
6

21_DPF_OM_EN_USC_t.book Page 287

288SAFETY
Trailer Tire Pressure Monitoring System
(TTPMS) — If Equipped
The Trailer Tire Pressure Monitoring System
(TTPMS) is a feature that displays the trailer tire
pressure values and warns the driver of a low
tire pressure event based on the drivers set
target tire pressure value, through TTPMS
settings found in the radio.

The TTPMS monitors the pressure of each tire
and warns the driver through the instrument
cluster, when either a low tire pressure condition
falls below 25% of the driver’s set pressure or if a
system malfunction occurs. The instrument
cluster will display the actual tire pressure or
dashes for each of the trailer tires in the correct
trailer position, based on trailer configuration.
The TTPMS can support up to 12 trailer tires per
configured trailer on up to four configurable
trailers
Ú
page 228. Trailer Tire Pressure Monitoring System

Trailer Tire Pressure Sensor Pairing
In order use this feature, the provided tire
pressure sensors must be installed in the
desired trailer tires and the sensors must be
paired to the truck. If the target trailer requires
more than the provided four sensors, additional
sensors can be purchased at an authorized
Ram dealership.
With the sensors installed and the trailer near
or connected to your Ram truck, initiate the
pairing process by entering the settings menu in
the radio and select trailer. Select the desired
trailer profile to pair to, open the “Tire Pressure”
menu, and hit “Setup All Tires” Ú page 228.NOTE:
The Vehicle may not be driven until the pairing
process is complete.

Trailer Tire Pressure SettingsTrailer Tire Pressure Pairing

21_DPF_OM_EN_USC_t.book Page 288