2008 JEEP WRANGLER wheel size

Also, the ORC turns on the Airbag Warning
Light for six to eight seconds for a self-check
when the ignition is first turned on. After the
self-check, the Airbag Warning Light will
turn off. If the ORC detects a malfunction in any part
of the system, it turns on the Airbag Warning Light
either momentarily or continuously. A single chime
will sound if the light comes on again after initial start
up.
WARNING!
Ignoring the Airbag Warning Light in your instru-
ment panel could mean you won’t have the airbags to
protect you in a collision. If the light does not come
on, stays on after you start the vehicle, or if it comes
on as you drive, have the airbag system checked
immediately.
•The Driver and Passenger Airbag/Inflator Units are
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. 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 to 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.
56 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE

40 mph (48 km/h), the normal ESP stability function
returns but TCS remains off. When the vehicle speed
drops below 35 mph (40 km/h), the ESP system shuts off.
ESP is off at low vehicle speeds in 4L range so that it will
not interfere with off-road driving, but the ESP function
returns to provide the stability feature at speeds above 40
mph (48 km/h). The ESP/TCS Indicator Light will al-
ways be illuminated in 4L range when ESP is off.
NOTE:The “ESP OFF” message will display and the
audible chime will sound when the shift lever is placed in
the PARK position from any position other than PARK,
and then moved out of the PARK position. This will
occur even if the message was previously cleared.WARNING!
With the ESP switched off, the enhanced vehicle
stability offered by ESP and ERM are unavailable. In
an emergency evasive maneuver, the ESP and ERM
systems will not engage to assist in maintaining
stability. The “Full Off” mode is intended for off-
road use only.
Disabling ESP for Modified Vehicles (4WD Models
Only)
Vehicles modified with larger tires and/or suspension
lifts may experience early ESP activations as compared to
a non-modified production vehicle depending on lift
size, tire size, suspension changes and/or driving habits.
If early ESP activations are experienced while driving a
modified vehicle, the additional ability to permanently
turn off ESP is available. A steering wheel/ESP button
UNDERSTANDING THE FEATURES OF YOUR VEHICLE 113
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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
of reasons, including the installation of replacement or
alternate tires or wheels on the vehicle that prevent the
TPMS from functioning properly. Always check the
TPMS malfunction telltale after replacing one or more
tires or wheels on your vehicle to ensure that the replace-
ment or alternate tires and wheels allow the TPMS to
continue to function properly.CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures and
warning have been established for the tire size
equipped on your vehicle. Undesirable system opera-
tion or sensor damage may result when using re-
placement equipment that is not of the same size,
type, and/or style. After-market wheels can cause
sensor damage. Do not use aftermarket tire sealants
or balance beads if your vehicle is equipped with a
TPMS, as damage to the sensors may result.
24. Odometer/Trip Odometer
The odometer shows the total distance the vehicle has
been driven.
UNDERSTANDING YOUR INSTRUMENT PANEL 211
4

rear wheels to rotate at the same speed. This is accom-
plished by simply moving the shift lever to one of these
positions. The 4H and 4L positions are intended for loose,
slippery road surfaces only, and not intended for normal
driving. Driving in the 4H and 4L positions on hard
surfaced roads will cause increased tire wear and damage
to the driveline components.
The 4WD Indicator Light (located in the instrument
cluster) alerts the driver that the vehicle is in four-wheel
drive, and the front and rear driveshafts are locked
together. The light will illuminate when the transfer case
is shifted into the 4H position.
NOTE:Do not attempt to shift when only the front or
rear wheels are spinning. The transfer case is not
equipped with a synchronizer, and the front and rear
driveshaft speeds must be equal for a shift to take place.
Shifting while only the front or rear wheels are spinning
can cause damage to the transfer case. When operating your vehicle in 4L, the engine speed will
be approximately three times (four times for Rubicon
models) that of the 2H or 4H positions at a given road
speed. Take care not to overspeed the engine.
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.
286 STARTING AND OPERATING

the load on the transmission locking mechanism may
make it difficult to move the shifter out of PARK.
WARNING!
•Always fully apply the parking brake when leav-
ing your vehicle, or it may roll and cause damage
or injury. Also, be certain to leave an automatic
transmission in PARK, a manual transmission in
REVERSE or 1st gear. Failure to do so may allow
the vehicle to roll and cause damage or injury.
•Never leave children alone in a vehicle. Leaving
unattended children in a vehicle is dangerous for a
number of reasons. A child or others could be
seriously or fatally injured. Do not leave the key in
the ignition. A child could operate power win-
dows, other controls, or move the vehicle.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.
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5

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 for any reason, your
foot is on the brake when the vehicle reaches 12 mph (20
km/h), this check will be delayed until 25 mph (40
km/h).
The Anti-Lock Brake System pump motor runs during
the self-test, and during an ABS stop, to provide the
regulated hydraulic pressure. The motor pump makes a
low humming noise during operation, this is normal. During off-road use, loss of traction can temporarily
defeat the system and cause the warning light to illumi-
nate. Turn the ignition OFF and ON again to restore
Anti-Lock Brake System function.
WARNING!
Pumping of the Anti-Lock Brakes will diminish their
effectiveness and may lead to an accident. Pumping
makes the stopping distance longer. Just press firmly
on your brake pedal when you need to slow down or
stop.
310 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 suspension
dimensions and performance characteristics, result-
ing 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 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 ad-
equate 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
readings.
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.
328 STARTING AND OPERATING

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
Install chains on rear tires only. Tire chains may be
installed on all models except the Sahara and Rubicon.
Follow these recommendations to guard against damage
and excessive tire and chain wear:
•Use chains on P225/75R16 tires only. P245/75R16,
P255/75R17, P255/70R18, and LT255/75R17 tires do
not provide adequate clearance.
•Use SAE class “S” tire chains or traction devices only.
•Chains must be the proper size for the vehicle, as
recommended by the chain manufacturer.
•Follow tire chain manufacturer’s instructions for
mounting chains.
•Install chains snugly and tighten after 0.6 mi (1 km) of
driving.
•Do notexceed 30 mph (48 km/h).
•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.
STARTING AND OPERATING 329
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