2007 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.
This vehicle is equipped with window bags to protect the
driver, front, and rear passengers sitting next to a win-
dow. They are located above the side windows. Their
covers are also labeled SRS/AIRBAG.
Front Airbag Components
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 43
2

•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
airbag gas is vented through the vent holes in the sides
of the airbag. In this way, the airbags do not interfere
with your control of the vehicle.•TheSide Impact SRS Side Curtain Airbagsare de-
signed to activate only in certain side or rollover
collisions. When the ORC (with side impact option)
detects a collision requiring the side curtain airbag to
inflate, it signals the inflators on the crash side of the
vehicle. A quantity of nontoxic gas is generated to
inflate the side curtain airbag. The inflating side cur-
tain airbag pushes the outside edge of the headliner
out of the way and covers the window. The airbag
inflates in about 30 milliseconds (about one quarter of
the time it takes to blink your eyes) with enough force
to injure you if you are not belted and seated properly,
or if items are positioned in the area where the side
curtain airbag inflates. This especially applies to chil-
dren. The side curtain airbag is only about 3
12inches
(9 cm) thick when it is inflated.
•TheKnee Impact Bolstershelp protect the knees of
the driver and the front passenger, and position every-
one for the best interaction with the front airbag.
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 49
2

CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures and
warnings have been established for the tire size
equipped on your vehicle. Undesirable system op-
eration or sensor 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
TPMS, as damage to the sensors may result.
13. Temperature Gauge
The temperature gauge shows engine coolant tempera-
ture. Any reading within the normal range indicates that
the engine cooling system is operating satisfactorily.The gauge pointer will likely indicate a higher tempera-
ture when driving in hot weather, up mountain grades,
or when towing a trailer. It should not be allowed to
exceed the upper limits of the normal operating range.
CAUTION!
Driving with a hot engine cooling system could
damage your vehicle. If temperature gauge reads (H),
pull over and stop the vehicle. Idle the vehicle with
the air conditioner turned off until the pointer drops
back into the normal range. If the pointer remains on
the “H”, and you hear continuous chimes, turn the
engine off immediately, and call for service.
UNDERSTANDING YOUR INSTRUMENT PANEL 179
4

percent of engine torque to the rear axle. When speed
differences are increased between the front and rear drive
shafts, 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.
Because four wheel drive provides improved traction,
there is a tendency to exceed safe turning and stopping
speeds. Do not go faster than road conditions permit.
STARTING AND OPERATING 263
5

When parking on a hill, turn the front wheels toward the
curb on a downhill grade and away from the curb on an
uphill grade.
The parking brake should always be applied whenever
the driver is not in the vehicle.
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.
274 STARTING AND OPERATING

CAUTION!
Prolonged operation of the steering system at the
end of the steering wheel travel will increase the
steering fluid temperature and it should be avoided
when possible. Damage to the power steering pump
may occur.
MULTI DISPLACEMENT SYSTEM (MDS) - 5.7L
Engine Only
This feature offers improved fuel economy by shutting
off four of the engine’s eight cylinders during light load
and cruise conditions. The system is automatic with no
driver inputs or additional driving skills required.
NOTE:The MDS system may take some time to return
to full functionality after a battery disconnect.
TIRE SAFETY INFORMATION
Tire Markings
NOTE:
•P (Passenger)-Metric tire sizing is based on U.S. design
standards. P-Metric tires have the letter “P” molded
into the sidewall preceding the size designation. Ex-
ample: P215/65R15 95H.
278 STARTING AND OPERATING

WARNING!
•Do not use a tire, wheel size or rating other than that
specified for your vehicle. Some combinations of
unapproved tires and wheels may change suspen-
sion dimensions and performance characteristics,
resulting in changes to steering, handling, and brak-
ing of your vehicle. This can cause unpredictable
handling and stress to steering and suspension com-
ponents. 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 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 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.
CAUTION!
Replacing original tires with tires of a different size
may result in false speedometer and odometer read-
ings.
Alignment and Balance
Poor suspension alignment may result in:
•Fast tire wear.
•Uneven tire wear, such as feathering and one-sided
wear.
•Vehicle pull to right or left.
Tires may also cause the vehicle to pull left or right.
Alignment will not correct this problem. See your autho-
rized dealer for proper diagnosis.
STARTING AND OPERATING 293
5

Improper alignment will not cause vehicle vibration.
Vibration may be a result of tire and wheel out-of-
balance. Proper balancing will reduce vibration and
avoid tire cupping and spotty wear.
TIRE CHAINS
Certain models have sufficient tire-to-body clearance to
allow use of tire chains.Install chains on rear tires only.
Follow these recommendations to guard against damage
and excessive tire and chain wear:
•Do not install tire chains or traction devices on ve-
hicles with larger than P235/65R17 size tires. Tires
larger than this may not provide sufficient body
clearance with chains or other traction devices.
•Use SAE class “S” tire chains or traction devices only.
•Follow tire chain manufacturer’s instructions for
mounting chains.
•Install chains snugly and tighten after 1/2 mile (1 km)
of driving.
•Do notexceed 35 mph (56 km/h), unless otherwise
specified by the chain manufacturer.
•Drive cautiously, avoiding large bumps, potholes and
extreme driving maneuvers.
TIRE ROTATION RECOMMENDATIONS
Tires on the front and rear axles of vehicles operate at
different loads and perform different steering, handling,
and braking functions. For these reasons, they wear at
unequal rates, and develop irregular wear patterns.
These effects can be reduced by timely rotation of tires.
The benefits of rotation are especially worthwhile with
aggressive tread designs such as those on On/Off Road
type tires. Rotation will increase tread life, help to main-
tain mud, snow, and wet traction levels, and contribute to
a smooth, quiet ride.
294 STARTING AND OPERATING