2008 JEEP GRAND CHEROKEE inflation pressure

12. Tire Pressure Monitoring Telltale Light
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recommended
by the vehicle manufacturer on the vehicle
placard or tire inflation pressure label. (If your vehicle
has tires of a different size than the size indicated on the
vehicle placard or tire inflation pressure label, you should
determine the proper tire inflation pressure for those
tires.)
As an added safety feature, your vehicle has been
equipped with a tire pressure monitoring system (TPMS)
that illuminates a low tire pressure telltale when one or
more of your tires are significantly under-inflated. Ac-
cordingly, when the low tire pressure telltale illuminates,
you should stop and check your tires as soon as possible,
and inflate them to the proper pressure. Driving on a
significantly under-inflated tire causes the tire to over-
heat and can lead to tire failure. Under-inflation alsoreduces fuel efficiency and tire tread life, and may affect
the vehicle's handling and stopping ability.
Please note that the TPMS is not a substitute for proper
tire maintenance, and it is the driver 's responsibility to
maintain correct tire pressure, even if under-inflation has
not reached the level to trigger illumination of the TPMS
low tire pressure telltale.
Your vehicle has also been equipped with a TPMS
malfunction indicator to indicate when the system is not
operating properly. The TPMS malfunction indicator is
combined with the low tire pressure telltale. When the
system detects a malfunction, the telltale will flash for
approximately one minute and then remain continuously
illuminated. This sequence will continue upon subse-
quent vehicle start-ups as long as the malfunction exists.
When the malfunction indicator is illuminated, the sys-
tem may not be able to detect or signal low tire pressure
as intended. TPMS malfunctions may occur for a variety
UNDERSTANDING YOUR INSTRUMENT PANEL 177
4

NOTE:Tires heat up during normal driving conditions.
Heat will cause the tire pressure to increase from 2 to 6
psi (14 to 41 kPa) during normal driving conditions. Refer
to ªTire Inflation Pressuresº in Section 5 for additional
information.NOTE:Your system can be set to display pressure units
in PSI, kPa, or BAR.
RADIO GENERAL INFORMATION
Radio Broadcast Signals
Your new radio will provide excellent reception under
most operating conditions. Like any system, however, car
radios have performance limitations, due to mobile op-
eration and natural phenomena, which might lead you to
believe your sound system is malfunctioning. To help
you understand and save you concern about these ªap-
parentº malfunctions, you must understand a point or
two about the transmission and reception of radio sig-
nals.
Tire Pressure Display
UNDERSTANDING YOUR INSTRUMENT PANEL 195
4

mTire Safety Information...................259
NTire Markings........................259
NTire Identification Number (TIN)..........262
NTire Loading And Tire Pressure...........263
mTires Ð General Information...............267
NRun Flat Tires........................267
NTire Pressure.........................267
NTire Inflation Pressures.................269
NTire Pressures For High Speed Operation....270
NRadial-Ply Tires......................271
NTire Spinning........................271
NTread Wear Indicators..................272
NLife Of Tire.........................272NReplacement Tires.....................273
NAlignment And Balance.................274
mTire Rotation Recommendations............275
mTire Pressure Monitor System (TPMS)........275
NPremium System......................275
NGeneral Information...................278
mFuel Requirements......................278
N6.1L Engine.........................278
NReformulated Gasoline.................279
NGasoline/Oxygenate Blends..............279
NMMT In Gasoline.....................280
NMaterials Added To Fuel................280
NFuel System Cautions..................280
240 STARTING AND OPERATING

EXAMPLE:
Service Description:
95= Load Index
ÐA numerical code associated with the maximum load a tire can carry.
H= Speed Symbol
ÐA symbol indicating the range of speeds at which a tire can carry a load corresponding
to its load index under certain operating conditions.
ÐThe maximum speed corresponding to the Speed Symbol should only be achieved un-
der specified operating conditions (i.e. tire pressure, vehicle loading, road conditions, and
posted speed limits).
Load Identification:
(....blank....(= Absence of any text on sidewall of the tire indicates a Standard Load (SL) Tire
Extra Load (XL)= Extra Load (or Reinforced) Tire
Light Load= Light Load Tire
C,D,E= Load range associated with the maximum load a tire can carry at a specified pressure
Maximum LoadÐ Maximum Load indicates the maximum load this tire is designed to carry.
Maximum PressureÐ
Maximum Pressure indicates the maximum permissible cold tire inflation pressure for this tire.
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Tire Loading and Tire Pressure
Tire Placard Location
NOTE:The proper cold tire inflation pressure is listed
on either the face of the driver's door or the driver's side
ªBº pillar.
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) the total weight your vehicle can carry
3) the tire size designed for your vehicle
4) the cold tire inflation pressures for the front, rear,
and spare tires.
Tire Placard Location
Tire and Loading Information
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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 ªTire and Loading
Informationº placard and in the ªVehicle Loadingº sec-
tion of this manual.
NOTE:Under a maximum loaded vehicle condition,
gross axle weight ratings (GAWR's) for the front and rear
axles must not be exceeded. For further information on
GAWR's, vehicle loading, and trailer towing, refer to the
ªVehicle Loadingº section of this manual.
To determine the maximum loading conditions of your
vehicle, locate the statement ªThe combined weight of
occupants and cargo should never exceed XXX kg or XXX
lbs.º on the Tire and Loading Information placard. Thecombined 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 ªThe combined weight of occu-
pants and cargo should never exceed XXX poundsº 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 pas-
sengers from XXX kilograms or XXX pounds.
4. The resulting figure equals the available amount of
cargo and luggage load capacity. For example, if ªXXXº
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. (since 5 x 150 = 750,
and 1400 ± 750 = 650 lbs.)
264 STARTING AND OPERATING

WARNING!
Overloading of your tires is dangerous. Overloading
can cause tire failure, affect vehicle handling, and
increase your stopping distance. Use tires of the
recommended load capacity for your vehicle. Never
overload them.
TIRES Ð GENERAL INFORMATION
Run Flat Tires
This vehicle is equipped with run flat tires. Although the
tires are designed with a ªrun flatº feature that allows the
vehicle to be driven about 50 miles (80 km) at 55 mph (88
km/h), immediate service should be obtained.
WARNING!
Do not exceed 50 mph (80 km/h) if the ªTire Pressure
Monitoring Telltale Lightº is illuminated. Vehicle
handling and braking may be reduced. You could
have an accident and be severely or fatally injured.
NOTE:The ªrun flatº feature eliminates the need for a
spare tire or jack. This vehicle is not equipped with either
a spare tire or jack.
Tire Pressure
Proper tire inflation pressure is essential to the safe and
satisfactory operation of your vehicle. Three primary
areas are affected by improper tire pressure:
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1. SafetyÐ
WARNING!
Improperly inflated tires are dangerous and can cause
accidents.
²Under inflation increases tire flexing and can result in
tire failure.
²Over inflation reduces a tire's ability to cushion
shock. Objects on the road and chuck holes can cause
damage that results in tire failure.
²Unequal tire pressures can cause steering problems.
You could lose control of your vehicle.
²Overinflated or under inflated tires can affect vehicle
handling and can fail suddenly, resulting in loss of
vehicle control.
²Unequal tire pressures from one side of the vehicle to
the other can cause the vehicle to drift to the right or left.
Always drive with each tire properly inflated.
2. EconomyÐ
Improper inflation pressures can cause uneven wear
patterns to develop across the tire tread. These abnormal
wear patterns will reduce tread life resulting in a need for
earlier tire replacement. Under inflation also increases
tire rolling resistance and results in higher fuel consump-
tion.
3. Ride Comfort and Vehicle StabilityÐ
Proper tire inflation contributes to a comfortable ride.
Over inflation produces a jarring and uncomfortable ride.
Both under inflation and over inflation affect the stability
of the vehicle and can produce a feeling of sluggish
response or over responsiveness in the steering.
Unequal tire pressures can cause erratic and unpredict-
able steering response.
Unequal tire pressure from side to side may cause the
vehicle to drift left or right.
268 STARTING AND OPERATING