tire size RAM CHASSIS CAB 2021 User Guide

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.
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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.
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406SERVICING AND MAINTENANCE
2. Rotate the bulb socket a quarter turn and
pull it from the lamp assembly.

Removing Bulb Socket From Clearance Lamp

3. Pull the bulb straight from it's socket and replace.
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.

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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SERVICING AND MAINTENANCE407
Tire Sizing Chart
EXAMPLE:
Example Size Designation: P215/65R15XL 95H, 215/65R15 96H, LT235/85R16C, T145/80D18 103M, 31x10.5 R15 LT
P = Passenger car tire size based on US design standards, or
"....blank...." = Passenger car tire based on European design standards, or
LT = Light truck tire based on US design standards, or
T or S = Temporary spare tire or
31 = Overall diameter in inches (in)
215, 235, 145 = Section width in millimeters (mm)
65, 85, 80 = Aspect ratio in percent (%)
Ratio of section height to section width of tire, or
10.5 = Section width in inches (in)
R = Construction code
"R" means radial construction, or
"D" means diagonal or bias construction
15, 16, 18 = Rim diameter in inches (in)
Service Description:
95 = Load Index
A numerical code associated with the maximum load a tire can carry
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SERVICING AND MAINTENANCE409
Tire Identification Number (TIN)
The TIN may be found on one or both sides of the tire; however, the date code may only be on one side. Tires with white sidewalls will have the full TIN,
including the date code, located on the white sidewall side of the tire. Look for the TIN on the outboard side of black sidewall tires as mounted on the
vehicle. If the TIN is not found on the outboard side, then you will find it on the inboard side of the tire.
EXAMPLE:
DOT MA L9 ABCD 0301
DOT = Department of Transportation
This symbol certifies that the tire is in compliance with the US Department of Transportation tire safety standards and is approved for highway use
MA = Code representing the tire manufacturing location (two digits)
L9 = Code representing the tire size (two digits)
ABCD = Code used by the tire manufacturer (one to four digits)
03 = Number representing the week in which the tire was manufactured (two digits)
03 means the 3rd week
01 = Number representing the year in which the tire was manufactured (two digits)
01 means the year 2001
Prior to July 2000, tire manufacturers were only required to have one number to represent the year in which the tire was manufactured. Example:
031 could represent the 3rd week of 1981 or 1991
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410SERVICING AND MAINTENANCE
Tire Terminology And Definitions
Term Definition
B-pillarThe 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 three hours, or driven less than 1 mile (1.6 km) after sitting for a
minimum of three hours. 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 pressure 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 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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SERVICING AND MAINTENANCE411
Tire Loading And Tire Pressure
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.

Example Tire Placard Location (Door) Example Tire Placard Location (B-pillar)

Tire And Loading Information Placard

Tire And Loading Information Placard
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 Ú page 199.
NOTE:
Under a maximum loaded vehicle condition,
gross axle weight ratings (GAWRs) for the front
and rear axles must not be exceeded.
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412SERVICING AND MAINTENANCE
For further information on GAWRs, vehicle
loading, and trailer towing, refer to “Vehicle
Loading” in the “Starting And Operating”
section of this manual.

To determine the maximum loading conditions of
your vehicle, locate the statement “The combined
weight of occupants and cargo should never exceed
XXX kg or XXX lbs” 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 occupants and cargo should
never exceed XXX kg or XXX lbs.” on your
vehicle's placard.
(2) Determine the combined weight of
the driver and passengers that will be
riding in your vehicle.
(3) Subtract the combined weight of the
driver and passengers from XXX kg or
XXX lbs. (4) The resulting figure equals the
available amount of cargo and luggage
load capacity. For example, if “XXX”
amount equals 1400 lbs. and there will
be five 150 lb passengers in your
vehicle, the amount of available cargo
and luggage load capacity is 650 lbs.
(1400-750 (5x150) = 650 lbs.)
(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.
Metric Example For Load Limit
For example, if “XXX” amount equals 635 kg
and there will be five 68 kg passengers in your
vehicle, the amount of available cargo and
luggage load capacity is 295 kg (635-340
(5x68) = 295 kg) as shown in step 4.
NOTE:

If your vehicle will be towing a trailer, load from
your trailer will be transferred to your vehicle.
The following table shows examples on how to
calculate 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).

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416SERVICING AND MAINTENANCE
Radial Ply Tires
Tire Repair
If your tire becomes damaged, it may be
repaired if it meets the following criteria:
The tire has not been driven on when flat.
The damage is only on the tread section of
your tire (sidewall damage is not repairable).
The puncture is no greater than a ¼ of an
inch (6 mm).
Consult an authorized tire dealer for tire repairs
and additional information.

Damaged Run Flat tires, or Run Flat tires that have
experienced a loss of pressure should be replaced
immediately with another Run Flat tire of identical
size and service description (Load Index and Speed
Symbol). Replace the tire pressure sensor as well as
it is not designed to be reused.

Run Flat Tires — If Equipped
Run Flat tires allow you the capability to drive
50 miles (80 km) at 50 mph (80 km/h) after a
rapid loss of inflation pressure. This rapid loss
of inflation is referred to as the Run Flat mode.
A Run Flat mode occurs when the tire inflation
pressure is of/or below 14 psi (96 kPa). Once a
Run Flat tire reaches the Run Flat mode it has
limited driving capabilities and needs to be
replaced immediately. A Run Flat tire is not
repairable. When a Run Flat tire is changed
after driving with underinflated tire condition,
please replace the TPM sensor as it is not
designed to be reused when driven under Run
Flat mode 14 psi (96 kPa) condition.
NOTE:
TPM Sensor must be replaced after driving the
vehicle on a flat tire condition.
It is not recommended driving a vehicle loaded
at full capacity or to tow a trailer while a tire is in
the Run Flat mode.
See the tire pressure monitoring section for
more information.
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.WARNING!

Combining radial ply tires with other types of tires
on your vehicle will cause your vehicle to handle
poorly. The instability could cause a collision.
Always use radial ply tires in sets of four. Never
combine them with other types of tires.

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.

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SERVICING AND MAINTENANCE417
Tread Wear Indicators
Tread wear indicators are in the original
equipment tires to help you in determining
when your tires should be replaced.

Tire Tread

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.
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 pres -
sures 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 scheduled maintenance is
highly recommended. NOTE:
Wheel valve stem must be replaced as well
when installing new tires due to wear and tear
in existing tires.
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 manufacturer strongly recommends
that you use tires equivalent to the originals in size,
quality and performance when replacement is
needed

Ú
page 417. 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.

For more information relating to the Load Index
and Speed Symbol of a tire Ú page 406.
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.
1 — Worn Tire
2 — New Tire
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.
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