2021 RAM 1500 tire size

STARTING AND OPERATING215
Gross Trailer Weight (GTW)
The GTW is the weight of the trailer plus the
weight of all cargo, consumables and
equipment (permanent or temporary) loaded in
or on the trailer in its “loaded and ready for
operation” condition.
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 allowable weight of your
vehicle and trailer when weighed in
combination.
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
Ú
page 213.
Tongue Weight (TW)
The TW is the downward force exerted on the
hitch ball by the trailer. You must consider this
as part of the load on your vehicle.
Trailer Frontal Area
The frontal area is the maximum height
multiplied by the maximum width of the front of
a trailer.
Trailer Sway Control (TSC)
The TSC can be a mechanical telescoping link
that can be installed between the hitch receiver
and the trailer tongue that typically provides
adjustable friction associated with the
telescoping motion to dampen any unwanted
trailer swaying motions while traveling. If equipped, the electronic TSC recognizes a
swaying trailer and automatically applies
individual wheel brakes and/or reduces engine
power to attempt to eliminate the trailer sway.
Weight-Carrying Hitch
A weight-carrying hitch supports the trailer
tongue weight, just as if it were luggage located
at a hitch ball or some other connecting point of
the vehicle. These kinds of hitches are
commonly used to tow small and medium sized
trailers.
Weight-Distributing Hitch
A weight-distributing system works by applying
leverage through spring (load) bars. They are
typically used for heavier loads to distribute
trailer tongue weight to the tow vehicle's front
axle and the trailer axle(s). When used in
accordance with the manufacturer's directions,
it provides for a more level ride, offering more
consistent steering and brake control, thereby
enhancing towing safety. The addition of a
friction/hydraulic sway control also dampens
sway caused by traffic and crosswinds and
contributes positively to tow vehicle and trailer
stability. Trailer sway control and a weight
distributing (load equalizing) hitch are
WARNING!

If the gross trailer weight is 5,000 lbs (2,267 kg)
or more, it is recommended to use a weight-dis
-
tributing hitch to ensure stable handling of your
vehicle. If you use a standard weight-carrying
hitch, you could lose control of your vehicle and
cause a collision.

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 vehi -
cle and have a collision.
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222STARTING AND OPERATING
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.
Replacing tires with a higher load carrying
capacity will not increase the vehicle's GVWR
and GAWR limits.
For further information Ú page 443.
Towing Requirements — Trailer Brakes
Do not interconnect the hydraulic brake
system or vacuum system of your vehicle
with that of the trailer.
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).
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)WARNING!
Do not connect trailer brakes to your
vehicle's hydraulic brake lines. It can over -
load your brake system and cause it to fail.
You might not have brakes when you need
them and could have an accident.
Towing any trailer will increase your stop -
ping distance. When towing, you should
allow for additional space between your
vehicle and the vehicle in front of you.
Failure to do so could result in an accident.
CAUTION!

If the trailer weighs more than 1,000 lbs
(453 kg) loaded, it should have its own
brakes and they should be of adequate
capacity. Failure to do this could lead to
accelerated brake lining wear, higher brake
pedal effort, and longer stopping distances.
21_DT_OM_EN_USC_t.book Page 222

SAFETY313
(Continued)
ESC Operating Modes
Depending upon model and mode of operation,
the ESC system may have multiple operating
modes. ESC On
This is the normal operating mode for the ESC.
Whenever the vehicle is started, the ESC system
will be in this mode. This mode should be used
for most driving conditions. Alternate ESC
modes should only be used for specific reasons
as noted in the following paragraphs.
Partial Off
This mode may be useful if the vehicle becomes
stuck. This mode may modify TCS and ESC
thresholds for activation, which allows for more
wheel spin than normally allowed.
To enter the “Partial Off” mode, momentarily
push the ESC OFF switch and the ESC OFF
Indicator Light will illuminate. To turn the ESC
on again, momentarily push the ESC OFF switch
and the ESC OFF Indicator Light will turn off.
NOTE:
For vehicles with multiple partial ESC modes,
the push and release of the button will toggle
the ESC modes. Multiple attempts may be
required to return to “ESC On”.
WARNING!
Electronic Stability Control (ESC) cannot
prevent the natural laws of physics from
acting on the vehicle, nor can it increase
the traction afforded by prevailing road
conditions. ESC cannot prevent accidents,
including those resulting from excessive
speed in turns, driving on very slippery
surfaces, or hydroplaning. ESC also cannot
prevent accidents resulting from loss of
vehicle control due to inappropriate driver
input for the conditions. Only a safe, atten
-
tive, and skillful driver can prevent acci -
dents. The capabilities of an ESC equipped
vehicle must never be exploited in a reck -
less or dangerous manner which could
jeopardize the user’s safety or the safety of
others.Vehicle modifications, or failure to properly
maintain your vehicle, may change the
handling characteristics of your vehicle,
and may negatively affect the performance
of the ESC system. Changes to the steering
system, suspension, braking system, tire
type and size or wheel size may adversely
affect ESC performance. Improperly
inflated and unevenly worn tires may also
degrade ESC performance. Any vehicle
modification or poor vehicle maintenance
that reduces the effectiveness of the ESC
system can increase the risk of loss of
vehicle control, vehicle rollover, personal
injury and death.
WARNING! (Continued)
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SAFETY323
a trailer will be detected using the blind spot
radar within 90 seconds of forward move -
ment of the vehicle. The vehicle must be
moving above 6 mph (10 km/h) to activate the feature. Once the trailer has been
detected, the system will default to the
maximum blind spot zone until the length has
been verified. You will see “Auto” in the
instrument panel cluster .
Maximum Mode — When “Max Mode” is
selected, the system will default to the
maximum blind spot zone regardless of what
size trailer is attached .
NOTE:
Selected setting is stored when the ignition is
placed in the OFF position. To change this
setting, it must be selected through the
Uconnect settings Ú page 237.
Trailer Length Detection
Once the trailer presence has been established,
the trailer length will be established (by making
a 90 degree turn) and then the trailer length
category (example 10-20 ft (3 m to 6 m)) will be
displayed. This can take up to 30 seconds after
completing the turn. NOTE:
During the same ignition cycle, if the vehicle is
at a standstill for a minimum of 90 seconds, a
new “trailer detection request” is enabled by
the system once the vehicle resumes motion.
Maximum length supported by the Trailer Merge
Assist feature is 39.5 ft (12 m). Trailer length is
considered the forward most portion of the
trailer hitch to the rearward most portion of the
body, fascia/bumper, or ramp of the trailer.
Maximum width supported by the Trailer Merge
Assist feature is 8.5 ft (2.59 m). Trailer width is
measured at the widest portion of the trailer
and may include wheels, tires, finders, or rails.
NOTE:
Fifth wheel or gooseneck trailers are not
supported by Trailer Merge Assist.
NOTE:
The ability to detect a trailer may be degraded in
crowded or busy environments. Busy parking
lots, narrow areas surrounded with trees, or any
other crowded area may prevent the radar
sensors from being able to adequately detect
the trailer. The system will try to detect a trailer
at every ignition cycle or 90 seconds of stand
-
still.
Trailer Length Detection

Trailer length will be identified and placed into
one of the following categories:
Trailer length up to 10 ft (3 m) — Blind spot
zone will be adjusted to 10 ft (3 m) .
Trailer length between 10 ft to 20 ft (3 m to
6 m) — Blind spot zone will be adjusted to
20 ft (6 m) .
Trailer length between 20 ft to 30 ft (6 m to
9 m) — Blind spot zone will be adjusted to
30 ft (9 m) .
1 — Trailer Length
2 — Trailer Width
3 — Trailer Hitch
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328SAFETY
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 443 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 Ú page 482.
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, 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.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.

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330SAFETY
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 (TPMS) 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 "SERVICE TPMS 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 TPMS
SYSTEM" message will no longer display, and a
pressure 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 Tire Pressure Moni
-
toring System 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
(TPMS) 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 Warning Light” will
no longer flash and the tire pressure display
screen will be displayed showing the tire
pressure values 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

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SAFETY331
warning limit, upon the next ignition switch
cycle, the Tire Pressure Monitoring System
(TPMS) Warning Light and a “LOW TIRE”
message will remain on and a chime will
sound. In addition, the graphic in the instru -
ment 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 Tire Pressure
Monitoring System (TPMS) Warning Light will
flash on and off for 75 seconds and then
remain on solid. In addition, the instrument
cluster will display a "SERVICE TPMS
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 Tire Pressure Moni -
toring System (TPMS) Warning Light will flash
on and off for 75 seconds and then remain
on solid, and the instrument cluster will
display a "SERVICE TPMS 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 Tire Pressure Monitoring
System (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.
Tire Fill Alert
This feature notifies the user when the placard
tire pressure is attained while inflating or
deflating the tire.
You may choose to disable or enable the Tire Fill
Alert feature through use of the Uconnect
Settings in the radio.
NOTE:
Only one tire can be filled at a time when
using the Tire Fill Alert system.
The Tire Fill Alert feature cannot be entered if
an existing TPMS fault is set to “active” or if
the system is in deactivation mode (if
equipped).
The system will be activated when a positive
increase in tire pressure is detected by the
TPMS while inflating the tire. The ignition must
be in the RUN mode, with the transmission in
PARK.
NOTE:
It is not required to have the engine running to
enter Tire Fill Alert mode.
The hazard lamps will come on to confirm the
vehicle is in Tire Fill Alert mode.
When Tire Fill Alert mode is entered, the tire
pressure display screen will be displayed in the
instrument cluster.
If the hazard lamps do not come on while
inflating the tire, the TPMS sensor may be out of
range preventing the TPMS sensor signal from
being received. In this case, the vehicle may
need to be moved either forward or backward
slightly to exit the null spot.
6

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SERVICING AND MAINTENANCE443
3. Turn the desired bulb socket a quarter turn
counterclockwise and remove the socket
and bulb from housing.
4. Pull the desired bulb straight from the socket.
Outside Bulbs: Cargo Lamps
Inside Bulb: Center High Mounted Stop
Lamp
5. Reverse the procedure for installation of bulbs and housing.
TIRES
TIRE SAFETY INFORMATION
Tire safety information will cover aspects of the
following information: Tire Markings, Tire
Identification Numbers, Tire Terminology and
Definitions, Tire Pressures, and Tire Loading.
Tire Markings

Tire Markings

NOTE:
P (Passenger) — Metric tire sizing is based on
US design standards. P-Metric tires have the
letter “P” molded into the sidewall preceding
the size designation. Example: P215/65R15
95H.
European — Metric tire sizing is based on
European design standards. Tires designed
to this standard have the tire size molded
into the sidewall beginning with the section
width. The letter "P" is absent from this tire
size designation. Example: 215/65R15 96H.
LT (Light Truck) — Metric tire sizing is based
on US design standards. The size designation
for LT-Metric tires is the same as for P-Metric
tires except for the letters “LT” that are
molded into the sidewall preceding the size
designation. Example: LT235/85R16.
Temporary spare tires are designed for
temporary emergency use only. Temporary
high pressure compact spare tires have the
letter “T” or “S” molded into the sidewall
preceding the size designation. Example:
T145/80D18 103M.
High flotation tire sizing is based on US
design standards and it begins with the tire
diameter molded into the sidewall. Example:
31x10.5 R15 LT.
CAUTION!
Do not contaminate the bulb glass by
touching it with your fingers or by allowing it
to contract other oily surfaces. Shortened
bulb life will result.
1 — US DOT Safety Standards Code (TIN)
2 — Size Designation
3 — Service Description
4 — Maximum Load
5 — Maximum Pressure
6 — Treadwear, Traction and Tempera -
ture Grades
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