tire size RAM CHASSIS CAB 2022 User Guide

SAFETY269
(Continued)
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 412.
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 effi -
ciency 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 responsibility
to maintain correct tire pressure using an accu -
rate tire pressure gauge, even if underinflation
has not reached the level to trigger illumination
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.
CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures
and warning have been established 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 pressure
always reinstall the valve stem cap. This will
prevent moisture and dirt from entering the
valve stem, which could damage the TPMS
sensor.
CAUTION!
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SAFETY271
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 Warning 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. There -
fore, 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 addi-
tion, 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 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.
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-pres -
sure 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.
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 driver’s 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 6

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376SERVICING 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 Euro -
pean design standards. Tires designed to this
standard have the tire size molded into the side -
wall 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 tempo -
rary emergency use only. Temporary high pres -
sure 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
Temperature Grades

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SERVICING AND MAINTENANCE377
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
H = Speed Symbol
A symbol indicating the range of speeds at which a tire can carry a load corresponding to its load index under certain operating conditions
The maximum speed corresponding to the speed symbol should only be achieved under specified operating conditions (i.e., tire pressure, vehicle loading,
road conditions, and posted speed limits)
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378SERVICING AND MAINTENANCE
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.Load Identification:
Absence of the following load identification symbols on the sidewall of the tire indicates a Standard Load (SL) tire:
XL = Extra load (or reinforced) tire, or
LL
= Light load tire or
C, D, E, F, G = Load range associated with the maximum load a tire can carry at a specified pressure
Maximum Load – Maximum load indicates the maximum load this tire is designed to carry
Maximum Pressure – Maximum pressure indicates the maximum permissible cold tire inflation pressure for this tire
EXAMPLE:
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

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SERVICING AND MAINTENANCE379
Tire Terminology And Definitions
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
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.
EXAMPLE:
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380SERVICING AND MAINTENANCE
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
Úpage 172.
NOTE:Under a maximum loaded vehicle condition, gross
axle weight ratings (GAWRs) for the front and rear
axles must not be exceeded.
For further information on GAWRs, vehicle loading,
and trailer towing Ú page 172.

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SERVICING AND MAINTENANCE381
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 occu
-
pants. 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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384SERVICING AND MAINTENANCE
Inflation pressures specified on the placard are
always “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. The cold
tire inflation pressure must not exceed the
maximum inflation pressure molded into the tire
sidewall.
Check tire pressures more often if subject to a
wide range of outdoor temperatures, as tire
pressures vary with temperature changes.
Tire pressures change by approximately 1 psi
(7 kPa) per 12°F (7°C) of air temperature change.
Keep this in mind when checking tire pressure
inside a garage, especially in the Winter.
Example: If garage temperature = 68°F (20°C)
and the outside temperature = 32°F (0°C) then
the cold tire inflation pressure should be increased
by 3 psi (21 kPa), which equals 1 psi (7 kPa) for
every 12°F (7°C) for this outside temperature
condition.
Tire pressure may increase from 2 to 6 psi (13 to
40 kPa) during operation. DO NOT reduce this
normal pressure build up or your tire pressure will
be too low.
Tire Pressures For High Speed Operation
The manufacturer advocates driving at safe
speeds and within posted speed limits. Where
speed limits or conditions are such that the vehicle
can be driven at high speeds, maintaining correct
tire inflation pressure is very important. Increased
tire pressure and reduced vehicle loading may be
required for high-speed vehicle operation. Refer to
an authorized tire dealer or original equipment
vehicle dealer for recommended safe operating
speeds, loading and cold tire inflation pressures.
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
WARNING!
High speed driving with your vehicle under
maximum load is dangerous. The added strain
on your tires could cause them to fail. You could
have a serious collision. Do not drive a vehicle
loaded to the maximum capacity at continuous
speeds above 75 mph (120 km/h).
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.

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386SERVICING AND MAINTENANCE
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 385. 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 376.
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 an 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.
TIRE TYPES
All Season Tires — If Equipped
All Season tires provide traction for all seasons
(Spring, Summer, Autumn, and Winter). Traction
levels may vary between different all season tires.
All season tires can be identified by the M+S, M&S,
M/S or MS designation on the tire sidewall. Use all
season tires only in sets of four; failure to do so
may adversely affect the safety and handling of
your vehicle.
Summer Or Three Season Tires —
If Equipped
Summer tires provide traction in both wet and dry
conditions, and are not intended to be driven in
snow or on ice. If your vehicle is equipped with
Summer tires, be aware these tires are not
designed for Winter or cold driving conditions.
Install Winter tires on your vehicle when ambient
temperatures are less than 40°F (5°C) or if roads
are covered with ice or snow. For more
information, contact an authorized dealer.
WARNING!
Do not use a tire, wheel size, load rating, or
speed rating other than that specified for your
vehicle. Some combinations of unapproved
tires and wheels may change suspension
dimensions and performance characteristics,
resulting in changes to steering, handling, and
braking of your vehicle. This can cause unpre -
dictable handling and stress to steering and
suspension components. 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 over -
loading and failure. You could lose control and
have a collision.
Failure to equip your vehicle with tires having
adequate 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 readings.

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