2005 JEEP GRAND CHEROKEE wheel size

Driver And Front Passenger Supplemental
Restraint Systems (SRS)This vehicle has airbags for both the driver and right
front passenger as a supplement to the seat belt restraint
systems. The driver’s front airbag is mounted in the
steering wheel. The passenger side airbag is mounted in
the instrument panel, above the glove compartment. The
words SRS/AIRBAG are embossed on the airbag covers.
NOTE:The front airbags are certified to the Federal
regulations that allow less forceful deployment.
The front airbags have a multistage inflator design. This
may allow the airbag to have different rates of inflation
that are based on collision severity and occupant size.
Also, the front passenger airbag is certified to the Federal
regulations that define Occupant Classification (Refer to
Occupant Classification Systemin this section).
Front Airbag Components
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 37
2

•Front Acceleration Sensors
•Driver and Front Passenger Seat Belt Pretensioner
•Occupant Classification System (OCS) — Front Pas-
senger Seat Only
Occupant Classification Module
Passenger Airbag Disable (PAD) Indicator Light
Weight Sensors
How The Airbag System Works
•
TheOccupant Restraint Control (ORC) Modulede-
termines if a frontal collision is severe enough to
require the airbags to inflate. The front airbag inflators
are designed to provide different rates of airbag infla-
tion from direction provided by the ORC. The ORC
may also modify the rate of inflation based on theoccupant size provided by the Occupant Classification
Module. The ORC will not detect roll over, or rear
impacts.
The ORC also monitors the readiness of the electronic
parts of the system whenever the ignition switch is in
the START or ON positions. These include all of the
items listed above except the knee bolster, the instru-
ment panel, and the steering wheel and column. If the
key is in the LOCK position, in the ACC position, or
not in the ignition, the airbags are not on and will not
inflate.
Also, the ORC turns on the “Airbag Warning
Light” and “PAD Indicator Light” for 6 to 8
seconds for a self-check when the ignition is
first turned on. After the self-check, the
“Airbag Warning Light” will turn off. The “PAD
Indicator Light” will function normally (Refer toPas-
senger Airbag Disable (PAD) Indicator Lightin this
42 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE

If the front passenger seat is damaged in any way, it
should only be serviced by an authorized dealer. If the
seat is removed (or even if the seat attachment bolts are
loosened or tightened in any way), take the vehicle to an
authorized dealer.
If there is a fault present in the OCS, the “Airbag Warning
Light” (a red light located in the center of the instrument
cluster directly in front of the driver) will be turned on.
This indicates that you should take the vehicle to an
authorized dealer. The “Airbag Warning Light” is turned
on whenever there is fault that can affect the operation of
the airbag system. If there is a fault present in the OCS,
both the “PAD Indicator Light” and the “Airbag Warning
Light” are illuminated to show that the passenger airbag
is turned off until the fault is cleared. If an object is
lodged under the seat and interferes with operation of
the weight sensors, a fault will occur which turns on both
the “PAD Indicator Light” and the “Airbag WarningLight.” Once the lodged object is removed, the fault will
be automatically cleared after a short period of time.
•TheDriver and Passenger Airbag/Inflator Unitsare
located in the center of the steering wheel and the right
side of the instrument panel. When the ORC detects a
collision requiring the airbags, it signals the inflator
units. A large quantity of nontoxic gas is generated to
inflate the front airbags. Different airbag inflation rates
are possible, based on collision severity and occupant
size. The steering wheel hub trim cover and the upper
right side of the instrument panel separate and fold
out of the way as the bags inflate to their full size. The
bags fully inflate in about 50–70 milliseconds. This is
about half of the time it takes to blink your eyes. The
bags then quickly deflate while helping to restrain the
driver and front passenger.
The driver front airbag gas is vented through the vent
holes in the sides of the airbag. The passenger front
46 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE

and Traction Control, provides resistance to any wheel
that is slipping to allow additional torque transfer to
wheels with traction.
NOTE:The Quadra-Trac Isystem is not appropriate
for conditions where LOW range is recommended. Refer
to “Off-Road Driving Tips” in this section.
Quadra-Trac IIOperating
Instructions/Precautions — If Equipped
The Quadra-Trac IItransfer case is fully automatic in the
normal driving 4 HI mode. The Quadra-Trac IItransfer
case provides three mode positions — four wheel drive
high range, neutral, and four wheel drive low range.
This transfer case is fully automatic in the 4 HI mode.
This transfer case divides engine torque almost evenly
with 48 percent of engine torque to the front axle and 52
percent of engine torque to the rear axle. When speed
differences are increased between the front and rear driveshafts, the transfer case can transmit up to 100 percent of
available engine torque to the front or rear drive shafts.
When additional traction is required, the 4 LOW position
can be used to lock the front and rear driveshafts together
and force the front and rear wheels to rotate at the same
speed. The 4 LOW position is intended for loose, slippery
road surfaces only. Driving in the 4 LOW position on dry
hard surfaced roads may cause increased tire wear and
damage to driveline components.
When operating your vehicle in 4 LOW, the engine speed
is approximately three times that of the 4 HI position 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
cause damage to the transfer case.
240 STARTING AND OPERATING

To release the parking brake, pull up slightly, press the
center button, then lower the lever completely.
Be sure the parking brake is fully disengaged before
driving. Failure to do so can lead to brake failure.
NOTE:Parking brake adjustment and maintenance
should be performed by your authorized dealer.
ANTI-LOCK BRAKE SYSTEM
The Anti-Lock Brake System (ABS) is designed to aid the
driver in maintaining vehicle control under adverse
braking conditions. The system operates with a separate
computer to modulate hydraulic pressure to prevent
wheel lock-up and help avoid skidding on slippery
surfaces.
All vehicle wheels and tires must be the same size and
type and tires must be properly inflated to produce
accurate signals for the computer.
WARNING!
Significant over or under inflation of tires, or mixing
sizes of tires or wheels on the vehicle can lead to loss
of braking effectiveness.
The Anti-Lock Brake System conducts a low-speed self-
test at about 12 mph (20 km/h). If you have your foot
lightly on the brake while this test is occurring you may
feel slight pedal movement. The movement can be more
apparent on ice and snow. This is normal.
The Anti-Lock Brake System pump motor runs during
the self-test at 12 mph (20 km/h) and during an ABS stop.
The pump motor makes a low humming noise during
operation, which is normal.
246 STARTING AND OPERATING

WARNING!
•Do not use a tire, wheel size or rating other than that
specified for your vehicle. Some combinations of un-
approved tires and wheels may change suspension
dimensions and performance characteristics, resulting
in changes to steering, handling, and braking of your
vehicle. This can cause unpredictable handling and
stress to steering and suspension components. You
could lose control and have an accident resulting in
serious injury or death. Use only the tire and wheel
sizes with load ratings approved for your vehicle.
•Never use a tire smaller than the minimum tire size
listed on your vehicle’s tire label. Using a smaller tire
could result in tire overloading and failure. You
could lose control and have an accident.
•Failure to equip your vehicle with tires having
adequate speed capability can result in sudden tire
failure and loss of vehicle control.
•Overloading your tires is dangerous. Overloading
can cause tire failure. Use tires of the recommended
load capacity for your vehicle - never overload them.
CAUTION!
Replacing original tires with tires of a different size
may result in false speedometer and odometer read-
ings. Check with your dealer before replacing tires
with a different size.
Alignment and Balance
The suspension components of your vehicle should be
inspected and aligned when needed, to obtain maximum
tire tread life.
Poor suspension alignment may result in:
•reduced tread life;
•uneven tire wear, such as feathering and one-sided
wear;
•vehicle pull to the right or to the left.
268 STARTING AND OPERATING

Tires may also cause the vehicle to pull left or right.
Alignment will not correct this problem. See your dealer
for proper diagnosis of the problem.
Improper alignment will not normally cause vehicle
vibration, which may be a result of tire and wheel
out-of-balance. Proper balancing will reduce vibration
and avoid tire cupping and spotty wear.
TIRE PRESSURE MONITOR SYSTEM
Tire Pressure Monitoring — Base System
The Tire Pressure Monitor System (TPM) system 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 your tires regularly and to maintain
the proper pressure.The “Tire Pressure Monitoring Indicator Lamp”
will illuminate in the instrument cluster, and an
audible chime will be activated when one or more
tire pressures is low. The “Tire Pressure Monitoring
Indicator Lamp” will flash on and off for ten seconds
when a system fault is detected. The flash cycle will
repeat every ten minutes or until the fault condition is
removed and reset.
The Tire Pressure Monitoring System consists of the
following components:•Receiver Module
•5 Wheel Sensors (including Full Size Spare Tire)
•Amber Colored Tire Pressure Monitoring Indicator
Lamp
The system will consist of tire pressure monitoring
sensors attached to each wheel through the valve stem
mounting hole, a central receiver module and an amber
STARTING AND OPERATING 269
5

colored Indicator Lamp. A sensor is located in the spare
wheel if the vehicle is equipped with a matching full size
spare wheel and tire assembly.
NOTE:For vehicles with optional wheel/tire sizes and
significantly different tire placard pressures, the placard
pressure value and the low-pressure threshold value is
re-programmable at your authorized dealer to accommo-
date the customer selected wheel/tire combinations rec-
ommended by DaimlerChrysler Corporation.CAUTION!
The TPM system has been optimized for the original
equipment tires and wheels. TPM system pressures
have been established for the tire size equipped on
your vehicle. Undesirable system operation or sen-
sor damage may result when using replacement
equipment that is not of the same size, type, and/or
style. After-market wheels can cause sensor damage.
Do not use tire sealant from a can, or balance beads
if your vehicle is equipped with a TPM system, as
damage to the sensors may result.
270 STARTING AND OPERATING