2002 JEEP GRAND CHEROKEE flat tire

²Unsatisfactory ride
²Vehicle drift
For proper tire pressure specification refer to the
Tire Inflation Pressure Chart provided with the vehi-
cles Owners Manual. A Certification Label on the
drivers side door pillar provides the minimum tire
and rim size for the vehicle. The label also list the
cold inflation pressure for these tires at full load
operation
Tire pressures have been chosen to provide safe
operation, vehicle stability, and a smooth ride. Tire
pressure should be checked cold once a month. Tire
pressure decreases as the ambient temperature
drops. Check tire pressure frequently when ambient
temperature varies widely.
Tire inflation pressures are cold inflation pressure.
The vehicle must sit for at least 3 hours to obtain the
correct cold inflation pressure reading. Or be drivenless than one mile after sitting for 3 hours. Tire
inflation pressures may increase from 2 to 6 pounds
per square inch (psi) during operation. Do not reduce
this normal pressure build-up.
WARNING: OVER OR UNDER INFLATED TIRES CAN
AFFECT VEHICLE HANDLING AND TREAD WEAR.
THIS MAY CAUSE THE TIRE TO FAIL SUDDENLY,
RESULTING IN LOSS OF VEHICLE CONTROL.
DESCRIPTION - TIRE PRESSURE FOR HIGH
SPEED
Where speed limits allow the vehicle to be driven
at high speeds, correct tire inflation pressure is very
important. For speeds up to and including 120 km/h
(75 mph), tires must be inflated to the pressures
shown on the tire placard. For continuous speeds in
excess of 120 km/h (75 mph), tires must be inflated
to the maximum pressure specified on the tire side-
wall.
Vehicles loaded to the maximum capacity should
not be driven at continuous speeds above 75 mph
(120 km/h).
For emergency vehicles that are driven at speeds
over 90 mph (144 km/h), special high speed tires
must be used. Consult tire manufacturer for correct
inflation pressure recommendations.
DESCRIPTION - REPLACEMENT TIRES
The original equipment tires provide a proper bal-
ance of many characteristics such as:
²Ride
²Noise
²Handling
²Durability
²Tread life
²Traction
²Rolling resistance
²Speed capability
It is recommended that tires equivalent to the orig-
inal equipment tires be used when replacement is
needed.
Failure to use equivalent replacement tires may
adversely affect the safety and handling of the vehi-
cle.
The use of oversize tires may cause interference
with vehicle components. Under extremes of suspen-
sion and steering travel, interference with vehicle
components may cause tire damage.
WARNING: FAILURE TO EQUIP THE VEHICLE WITH
TIRES HAVING ADEQUATE SPEED CAPABILITY
CAN RESULT IN SUDDEN TIRE FAILURE.
Fig. 13 Under Inflation Wear
1 - THIN TIRE THREAD AREAS
Fig. 14 Over Inflation Wear
1 - THIN TIRE THREAD AREA
WJTIRES/WHEELS 22 - 7
TIRES (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRESSURE
GAUGES
A quality air pressure gauge is recommended to
check tire pressure. After checking the air pressure,
replace valve cap finger tight.
DIAGNOSIS AND TESTING - TREAD WEAR
INDICATORS
Tread wear indicators are molded into the bottom
of the tread grooves. When tread depth is 1.6 mm
(1/16 in.), the tread wear indicators will appear as a
13 mm (1/2 in.) band (Fig. 15).
Tire replacement is necessary when indicators
appear in two or more grooves or if localized balding
occurs.
DIAGNOSIS AND TESTING - TIRE WEAR
PATTERNS
Under inflation will cause wear on the shoulders of
tire. Over inflation will cause wear at the center of
tire.
Excessive camber causes the tire to run at an
angle to the road. One side of tread is then worn
more than the other (Fig. 16).
Excessive toe-in or toe-out causes wear on the
tread edges and a feathered effect across the tread
(Fig. 16).
DIAGNOSIS AND TESTING - TIRE NOISE OR
VIBRATION
Radial-ply tires are sensitive to force impulses
caused by improper mounting, vibration, wheel
defects, or possibly tire imbalance.
To find out if tires are causing the noise or vibra-
tion, drive the vehicle over a smooth road at varying
speeds. Note the noise level during acceleration and
deceleration. The engine, differential and exhaust
noises will change as speed varies, while the tire
noise will usually remain constant.
STANDARD PROCEDURE - REPAIRING LEAKS
For proper repairing, a radial tire must be removed
from the wheel. Repairs should only be made if the
defect, or puncture, is in the tread area (Fig. 17). The
tire should be replaced if the puncture is located in
the sidewall.
Deflate tire completely before removing the tire
from the wheel. Use lubrication such as a mild soap
solution when dismounting or mounting tire. Use
tools free of burrs or sharp edges which could dam-
age the tire or wheel rim.
Before mounting tire on wheel, make sure all rust
is removed from the rim bead and repaint if neces-
sary.
Install wheel on vehicle, and tighten to proper
torque specification (Refer to 22 - TIRES/WHEELS/
WHEELS - SPECIFICATIONS).
Fig. 15 Tread Wear Indicators
1 - TREAD ACCEPTABLE
2 - TREAD UNACCEPTABLE
3 - WEAR INDICATOR
22 - 8 TIRES/WHEELSWJ

SPARE TIRE
DESCRIPTION - SPARE / TEMPORARY TIRE
The temporary spare tire is designed for emer-
gency use only. The original tire should be repaired
or replaced at the first opportunity, then reinstalled.
Do not exceed speeds of 50 M.P.H. when using the
temporary spare tire. Refer to Owner's Manual for
complete details.
WHEELS
DESCRIPTION
The rim size is on the vehicle safety certification
label located on the drivers door shut face. The size
of the rim is determined by the drivetrain package.
Original equipment wheels/rims are designed for
operation up to the specified maximum vehicle capac-
ity.
All models use stamped steel, cast aluminum or
forged aluminum wheels. Every wheel has raised sec-
tions between the rim flanges and rim drop well
called safety humps (Fig. 18) .
Initial inflation of the tire forces the bead over
these raised sections. In case of rapid loss of air pres-
sure, the raised sections help hold the tire on the
wheel.
The wheel studs and nuts are designed for specific
applications. All aluminum and some steel wheels
have wheel stud nuts with an enlarged nose. This
enlarged nose is necessary to ensure proper retentionof the wheels. Do not use replacement studs or nuts
with a different design or lesser quality.
DIAGNOSIS AND TESTING - WHEEL
INSPECTION
Inspect wheels for:
²Excessive run out
²Dents or cracks
²Damaged wheel lug nut holes
²Air Leaks from any area or surface of the rim
NOTE: Do not attempt to repair a wheel by hammer-
ing, heating or welding.
If a wheel is damaged an original equipment
replacement wheel should be used. When obtaining
replacement wheels, they should be equivalent in
load carrying capacity. The diameter, width, offset,
pilot hole and bolt circle of the wheel should be the
same as the original wheel.
WARNING: FAILURE TO USE EQUIVALENT
REPLACEMENT WHEELS MAY ADVERSELY
AFFECT THE SAFETY AND HANDLING OF THE
VEHICLE. USED WHEELS ARE NOT RECOM-
MENDED. THE SERVICE HISTORY OF THE WHEEL
MAY HAVE INCLUDED SEVERE TREATMENT OR
VERY HIGH MILEAGE. THE RIM COULD FAIL WITH-
OUT WARNING.
STANDARD PROCEDURE - WHEEL
REPLACEMENT
The wheel studs and nuts are designed for specific
applications. They must be replaced with equivalent
parts. Do not use replacement parts of lesser quality
or a substitute design. All aluminum and some steel
wheels have wheel stud nuts which feature an
enlarged nose. This enlarged nose is necessary to
ensure proper retention of the aluminum wheels.
NOTE: Do not use chrome plated lug nuts with
chrome plated wheels.
Before installing the wheel, be sure to remove any
build up of corrosion on the wheel mounting surfaces.
Ensure wheels are installed with good metal-to-metal
contact. Improper installation could cause loosening
of wheel nuts. This could affect the safety and han-
dling of your vehicle.
To install the wheel, first position it properly on
the mounting surface. All wheel nuts should then be
tightened just snug. Gradually tighten them in
sequence to the proper torque specification.Never
use oil or grease on studs or nuts.
Wheels must be replaced if they have:
²Excessive runout
Fig. 18 Safety Rim
1 - FLANGE
2 - RIDGE
3 - WELL
22 - 10 TIRES/WHEELSWJ

²Bent or dented
²Leak air through welds
²Have damaged bolt holes
Wheel repairs employing hammering, heating, or
welding are not allowed.
Original equipment wheels are available through
your dealer. Replacement wheels from any other
source should be equivalent in:
²Load carrying capacity
²Diameter
²Width²Offset
²Mounting configuration
Failure to use equivalent replacement wheels may
affect the safety and handling of your vehicle.
Replacement withusedwheels is not recommended.
Their service history may have included severe treat-
ment.
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Lug Nut
1/2 X 20 with 60É Cone115-150 85-115 Ð
STUDS
REMOVAL
CAUTION: Do not use a hammer to remove wheel
studs.
(1) Raise and support vehicle.
(2) Remove wheel and tire assembly.
(3) Remove brake caliper, caliper adapter and
rotor,(Refer to 5 - BRAKES/HYDRAULIC/MECHAN-
ICAL/ROTORS - REMOVAL).
(4) Remove stud from hub with Remover C-4150A
(Fig. 19).
INSTALLATION
CAUTION: Do not use a hammer to remove wheel
studs.
(1) Install the new stud into the hub flange.
(2) Install the three washers onto the stud, then
install the lug nut with the flat side of the nut
against the washers.
(3) Tighten the lug nut until the stud is pulled
into the hub flange. Verify that the stud is properly
seated into the flange.
(4) Remove the lug nut and washers.
(5) Install the brake rotor, caliper adapter, and
caliper,(Refer to 5 - BRAKES/HYDRAULIC/ME-
CHANICAL/DISC BRAKE CALIPERS - INSTALLA-
TION).(6) Install the wheel and tire assembly, use new
lug nut on stud or studs that were replaced.
(7) Remove the support and lower vehicle.Fig. 19 Wheel Stud Removal
1 - REMOVER
2 - WHEEL STUD
WJTIRES/WHEELS 22 - 11
WHEELS (Continued)

TIRE PRESSURE MONITORING
DESCRIPTION
The EVIC will monitor the tire pressure signals
from the five tire sensors and determine if any tire
has gone below the low pressure threshold or raised
above the high pressure threshold. Refer to the table
below.
LOW TIRE PRESSURE THRESHOLDS
SYSTEM STATUS
INDICATORTIRE PRESSURE
ON 179 kPa (26 PSI)
OFF 214 kPa (31 PSI)
HIGH TIRE PRESSURE THRESHOLDS
SYSTEM STATUS
INDICATORTIRE PRESSURE
ON 310 kPa (45 PSI)
OFF 276 kPa (40 PSI)
The Remote Tire Pressure Monitors (RTPM) are
not internally serviceable. For a Sensor Failure or
Low Battery fault, the RTPM must be replaced.
OPERATION
If equipped with the Tire Pressure Monitoring Sys-
tem, each of the vehicle's five wheels will have a
valve stem with a pressure sensor and radio trans-
mitter built in. Signals from the tire pressure sensors
are received and interpreted by the Electronic Vehi-
cle Information Center (EVIC). A sensor in a
mounted wheel will broadcast its detected pressure
once per minute when the vehicle is moving faster
than 40 km/h (25 mph). The spare tire sensor will
broadcast once every hour. Each sensor's broadcast is
uniquely coded so that the EVIC can determine loca-
tion. The individual tire pressures can be displayed
graphically on the EVIC
DIAGNOSIS AND TESTING - TIRE PRESSURE
MONITORING SYSTEM
All Tire Pressure Monitoring System Faults are
specific to one location. If a9BATTERY LOW9or
9SENSOR FAILURE9fault is detected, the location
will be displayed. The appropriate sensor/transmitter
can then be replaced. If a single sensor/transmitter
cannot be detected by the EVIC, replace that sensor
transmitter. If none of the sensors/transmitters can
be detected, refer to symptoms in the EVIC section.
For additional system description and diagnosis,
refer to Tire Pressure Monitoring in the Body Diag-
nostic manual.
SENSOR
REMOVAL - TIRE PRESSURE SENSOR/
TRANSMITTER
(1) Remove the tire/wheel from the vehicle.
CAUTION: When removing the stick on balancing
weights from the wheel, do not use an abrasive
cleaner or a cleaner which will damage the protec-
tive finish on the wheel.
(2) Remove the balancing weights from the wheel.
NOTE: The cap used on this valve stem contains an
O-ring seal to prevent contamination and moisture
from entering the valve stem. Retain this valve stem
cap for re-use. Do not substitute a regular valve
stem cap in its place.
(3) Remove the cap from the valve stem.
NOTE: The valve stem used on this vehicle is made
of aluminum and the core is nickel plated brass.
The original valve stem core must be reinstalled
and not substituted for a valve stem core made of a
different material. This is required to prevent corro-
sion in the valve stem caused by the different met-
als.
(4) Using the appropriate tool, remove the core
from the valve stem (Fig. 20).
(5) Let the tire fully deflate.
Fig. 20 REMOVING VALVE STEM CORE - TYPICAL
1 - WHEEL
2 - VALVE STEM
3 - TIRE
4 - VALVE STEM CORE TOOL
22 - 12 TIRES/WHEELSWJ