2019 Ram 4500 Chassis Cab tire size

290 STARTING AND OPERATING
Adaptive Cruise Control (ACC) Operation
The speed control buttons (located on the right side of the
steering wheel) operate the ACC system.Adaptive Cruise Control Buttons
NOTE:
Any chassis/suspension or tire size modifications to the
vehicle will effect the performance of the Adaptive Cruise
Control and Forward Collision Warning System.
Activating Adaptive Cruise Control (ACC)
You can only engage ACC if the vehicle speed is above
0 mph (0 km/h).
The minimum set speed for the ACC system is 20 mph
(32 km/h).
When the system is turned on and in the ready state, the
instrument cluster display will read “ACC Ready.”
When the system is off, the instrument cluster display will
read “Adaptive Cruise Control (ACC) Off.”
NOTE:
You cannot engage ACC under the following conditions:
• When in Four-Wheel Drive Low.
• When you apply the brakes.
• When the parking brake is applied.
• When the automatic transmission is in PARK, REVERSE or NEUTRAL.
• When the vehicle speed is outside of the speed range.
• When the brakes are overheated.
1 — Adaptive Cruise Control On/Off Button
2 — Distance Button

338 STARTING AND OPERATING
Payload
The payload of a vehicle is defined as the allowable load
weight a truck can carry, including the weight of the driver,
all passengers, options and cargo.
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 insure 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 axle. Weighing the vehicle
may show that the GAWR of either the front or rear axles has
been exceeded but the total load is within the specified
GVWR. If so, weight must be shifted from front to rear or

STARTING AND OPERATING 347
(Continued)
Towing Requirements — Tires
• Do not attempt to tow a trailer while using a compact sparetire.
• Do not drive more than 50 mph (80 km/h) when towing while using a full size spare tire.
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 difficult 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. Overloading 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)
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SERVICING AND MAINTENANCE 445
Tire Markings
Tire Markings
NOTE:
• P (Passenger) — Metric tire sizing is based on U.S. designstandards. 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 U.S. 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 desig -
nation. Example: LT235/85R16.
• Temporary spare tires are designed for temporary emer -
gency 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 U.S. design standards and it begins with the tire diameter molded into the side -
wall. Example: 31x10.5 R15 LT.
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
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446 SERVICING AND MAINTENANCE
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 U.S. design standards, or
"....blank...." = Passenger car tire based on European design standards, or
LT = Light truck tire based on U.S. 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

448 SERVICING 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 side-
walls 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 U.S. 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

SERVICING AND MAINTENANCE 449
Tire Terminology And DefinitionsTerm Definition
B-Pillar The 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 MAINTENANCE 451
Tire And Loading Information PlacardTire 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 pres
-
sures specified on the Tire and Loading Information placard
in “Vehicle Loading” in the “Starting And Operating”
section of this manual.
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, 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 occu-
pants 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 refer -
enced here.
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