2018 JEEP WRANGLER UNLIMITED wheel size

speed. This range provides additional trac-
tion and maximum pulling power for loose,
slippery road surfaces only. Do not exceed
25 mph (40 km/h).
This transfer case is designed to be driven in
the two-wheel drive position (2WD) or four-
wheel drive position (4WD AUTO) for normal
street and highway conditions on dry hard
surfaced roads. Driving the vehicle in 2WD
will have greater fuel economy benefits as the
front axle is not engaged in 2WD.
For variable driving conditions, the 4WD
AUTO mode can be used. In this mode, the
front axle is engaged, but the vehicle's power
is sent to the rear wheels. Four-wheel drive
will be automatically engaged when the ve-
hicle senses a loss of traction. Because the
front axle is engaged, this mode will result in
lower fuel economy than the 2WD mode.
In the event that additional traction is re-
quired, the transfer case 4H and 4L positions
can be used to lock the front and rear drive-
shafts together, forcing the front and rear
wheels to rotate at the same speed. The 4H
and 4L positions are intended for loose, slip-
pery road surfaces only and not intended fornormal driving. Driving in the 4H and 4L
positions on hard-surfaced roads will cause
increased tire wear and damage to the drive-
line components. Refer to “Shifting Proce-
dures” in this section for further information
on shifting into 4H or 4L.
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.
When operating your vehicle in 4L, the en-
gine 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 dam-
age 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.Shifting Procedures
2H To 4H Auto Or 4H Auto To 2H
Shifting between 2H and 4H Auto can be
made with the vehicle stopped or in motion.
The preferred shifting speed would be 0 to
45 mph (72 km/h). With the vehicle in mo-
tion, the transfer case will engage/disengage
faster if you momentarily release the accel-
erator pedal after completing the shift. Do
not accelerate while shifting the transfer
case. Apply a constant force when shifting
the transfer case lever.
2H/4H Auto To 4H Part Time Or 4H Part Time
To 2H/4H Auto
Shifting between 2H/4H AUTO to 4H PART
TIME can be made with the vehicle stopped
or in motion. The preferred shifting speed
would be 0 to 45 mph (72 km/h). With the
vehicle in motion, the transfer case will
engage/disengage faster if you momentarily
release the accelerator pedal after complet-
ing the shift. Do not accelerate while shifting
the transfer case. Apply a constant force
when shifting the transfer case lever.
STARTING AND OPERATING
154

reduced vehicle loading may be required for
high-speed vehicle operation. Refer to an
authorized tire dealer or original equipment
vehicle dealer for recommended safe operat-
ing speeds, loading and cold tire inflation
pressures.
WARNING!
High speed driving with your vehicle under
maximum load is dangerous. The added
strain on your tires could cause them to
fail. You could have a serious collision. Do
not drive a vehicle loaded to the maximum
capacity at continuous speeds above
75 mph (120 km/h).
Radial Ply Tires
WARNING!
Combining radial ply tires with other types
of tires on your vehicle will cause your
vehicle to handle poorly. The instability
could cause a collision. Always use radial
ply tires in sets of four. Never combine
them with other types of tires.Tire Repair
If your tire becomes damaged, it may be
repaired if it meets the following criteria:
• The tire has not been driven on when flat.
• The damage is only on the tread section of
your tire (sidewall damage is not repair-
able).
• The puncture is no greater thana¼ofan
inch (6 mm).
Consult an authorized tire dealer for tire re-
pairs and additional information.
Damaged Run Flat tires, or Run Flat tires that
have experienced a loss of pressure should be
replaced immediately with another Run Flat
tire of identical size and service description
(Load Index and Speed Symbol).
Run Flat Tires — If Equipped
Run Flat tires allow you the capability to drive
50 miles (80 km) at 50 mph (80 km/h) after
a rapid loss of inflation pressure. This rapid
loss of inflation is referred to as the Run Flat
mode. A Run Flat mode occurs when the tire
inflation pressure is of/or below 14 psi
(96 kPa). Once a Run Flat tire reaches therun flat mode it has limited driving capabili-
ties and needs to be replaced immediately. A
Run Flat tire is not repairable.
It is not recommended driving a vehicle
loaded at full capacity or to tow a trailer while
a tire is in the run flat mode.
See the tire pressure monitoring section for
more information.
Tire Spinning
When stuck in mud, sand, snow, or ice con-
ditions, do not spin your vehicle's wheels
above 30 mph (48 km/h) or for longer than
30 seconds continuously without stopping.
Refer to “Freeing A Stuck Vehicle” in “In
Case Of Emergency” in your Owner’s Manual
for further information.
WARNING!
Fast spinning tires can be dangerous.
Forces generated by excessive wheel
speeds may cause tire damage or failure. A
tire could explode and injure someone. Do
not spin your vehicle's wheels faster than
SERVICING AND MAINTENANCE
232

WARNING!
30 mph (48 km/h) for more than 30 sec-
onds continuously when you are stuck,
and do not let anyone near a spinning
wheel, no matter what the speed.
Tread Wear Indicators
Tread wear indicators are in the original
equipment tires to help you in determining
when your tires should be replaced.
These indicators are molded into the bottom
of the tread grooves. They will appear as
bands when the tread depth becomes a
1/16 of an inch (1.6 mm). When the tread isworn to the tread wear indicators, the tire
should be replaced. Refer to “Replacement
Tires” in this section for further information.
Life Of Tire
The service life of a tire is dependent upon
varying factors including, but not limited to:
• Driving style.
• Tire pressure - Improper cold tire inflation
pressures can cause uneven wear patterns
to develop across the tire tread. These ab-
normal wear patterns will reduce tread life,
resulting in the need for earlier tire replace-
ment.
• Distance driven.
• Performance tires, tires with a speed rating
of V or higher, and Summer tires typically
have a reduced tread life. Rotation of these
tires per the vehicle scheduled mainte-
nance is highly recommended.
WARNING!
Tires and the spare tire should be replaced
after six years, regardless of the remaining
tread. Failure to follow this warning can
WARNING!
result in sudden tire failure. You could lose
control and have a collision resulting in
serious injury or death.
NOTE:
Wheel Valve Stem must be replaced as well
when installing new tires due to wear and tear
in existing tires.
Keep dismounted tires in a cool, dry place
with as little exposure to light as possible.
Protect tires from contact with oil, grease,
and gasoline.
Replacement Tires
The tires on your new vehicle provide a bal-
ance of many characteristics. They should be
inspected regularly for wear and correct cold
tire inflation pressures. The manufacturer
strongly recommends that you use tires
equivalent to the originals in size, quality and
performance when replacement is needed.
Refer to the paragraph on “Tread Wear Indi-
cators” in this section. Refer to the Tire and
Loading Information placard or the Vehicle
Certification Label for the size designation of
Tire Tread
1 — Worn Tire
2 — New Tire
233

your tire. The Load Index and Speed Symbol
for your tire will be found on the original
equipment tire sidewall.
It is recommended to replace the two front
tires or two rear tires as a pair. Replacing just
one tire can seriously affect your vehicle’s
handling. If you ever replace a wheel, make
sure that the wheel’s specifications match
those of the original wheels.
It is recommended you contact an authorized
tire dealer or original equipment dealer with
any questions you may have on tire specifi-
cations or capability. Failure to use equiva-
lent replacement tires may adversely affect
the safety, handling, and ride of your vehicle.
WARNING!
• Do not use a tire, wheel size, load rating,
or speed rating other than that specified
for your vehicle. Some combinations of
unapproved tires and wheels may
change suspension dimensions and per-
formance characteristics, resulting in
changes to steering, handling, and brak-
ing of your vehicle. This can cause un-
WARNING!
predictable handling and stress to steer-
ing and suspension components. You
could lose control and have a collision
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 origi-
nally equipped on your vehicle. Using a
tire with a smaller load index could re-
sult in tire overloading and failure. You
could lose control and have a collision.
• 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 speedom-
eter and odometer readings.
Tire Types
All Season Tires — If Equipped
All Season tires provide traction for all sea-
sons (Spring, Summer, Fall, and Winter).
Traction levels may vary between different all
season tires. All season tires can be identi-
fied by the M+S, M&S, M/S or MS designa-
tion on the tire sidewall. Use all season tires
only in sets of four; failure to do so may
adversely affect the safety and handling of
your vehicle.
Summer Or Three Season Tires — If
Equipped
Summer tires provide traction in both wet
and dry conditions, and are not intended to
be driven in snow or on ice. If your vehicle is
equipped with Summer tires, be aware these
tires are not designed for Winter or cold
driving conditions. Install Winter tires on your
vehicle when ambient temperatures are less
than 40°F (5°C) or if roads are covered with
ice or snow. For more information, contact an
authorized dealer.
Summer tires do not contain the all season
designation or mountain/snowflake symbol
SERVICING AND MAINTENANCE
234

on the tire sidewall. Use Summer tires only in
sets of four; failure to do so may adversely
affect the safety and handling of your vehicle.
WARNING!
Do not use Summer tires in snow/ice con-
ditions. You could lose vehicle control,
resulting in severe injury or death. Driving
too fast for conditions also creates the
possibility of loss of vehicle control.
Snow Tires
Some areas of the country require the use of
snow tires during the Winter. Snow tires can
be identified by a “mountain/snowflake”
symbol on the tire sidewall.
If you need snow tires,
select tires equivalent
in size and type to the
original equipment
tires. Use snow tires
only in sets of four;
failure to do so may
adversely affect the
safety and handling of your vehicle.Snow tires generally have lower speed ratings
than what was originally equipped with your
vehicle and should not be operated at sus-
tained speeds over 75 mph (120 km/h). For
speeds above 75 mph (120 km/h) refer to
original equipment or an authorized tire
dealer for recommended safe operating
speeds, loading and cold tire inflation pres-
sures.
While studded tires improve performance on
ice, skid and traction capability on wet or dry
surfaces may be poorer than that of non-
studded tires. Some states prohibit studded
tires; therefore, local laws should be checked
before using these tire types.
Spare Tires — If Equipped
For vehicles equipped with Tire Service Kit
instead of a spare tire, please refer to “Tire
Service Kit” in “In Case Of Emergency” in the
Owner’s Manual for further information.
CAUTION!
Because of the reduced ground clearance,
do not take your vehicle through an auto-
CAUTION!
matic car wash with a compact or limited
use temporary spare installed. Damage to
the vehicle may result.
Spare Tire Matching Original Equipped Tire
And Wheel — If Equipped
Your vehicle may be equipped with a spare
tire and wheel equivalent in look and function
to the original equipment tire and wheel
found on the front or rear axle of your vehicle.
This spare tire may be used in the tire rotation
for your vehicle. If your vehicle has this op-
tion, refer to an authorized tire dealer for the
recommended tire rotation pattern.
Compact Spare Tire — If Equipped
The compact spare is for temporary emer-
gency use only. You can identify if your ve-
hicle is equipped with a compact spare by
looking at the spare tire description on the
Tire and Loading Information Placard located
on the driver’s side door opening or on the
235

sidewall of the tire. Compact spare tire de-
scriptions begin with the letter “T” or “S”
preceding the size designation. Example:
T145/80D18 103M.
T,S=Temporary Spare Tire
Since this tire has limited tread life, the
original equipment tire should be repaired (or
replaced) and reinstalled on your vehicle at
the first opportunity.
Do not install a wheel cover or attempt to
mount a conventional tire on the compact
spare wheel, since the wheel is designed
specifically for the compact spare tire. Do not
install more than one compact spare tire and
wheel on the vehicle at any given time.
WARNING!
Compact and collapsible spares are for
temporary emergency use only. With these
spares, do not drive more than 50 mph
(80 km/h). Temporary use spares have
limited tread life. When the tread is worn
to the tread wear indicators, the temporary
use spare tire needs to be replaced. Be
sure to follow the warnings, which apply to
WARNING!
your spare. Failure to do so could result in
spare tire failure and loss of vehicle con-
trol.
Full Size Spare — If Equipped
The full size spare is for temporary emer-
gency use only. This tire may look like the
originally equipped tire on the front or rear
axle of your vehicle, but it is not. This spare
tire may have limited tread life. When the
tread is worn to the tread wear indicators, the
temporary use full size spare tire needs to be
replaced. Since it is not the same as your
original equipment tire, replace (or repair)
the original equipment tire and reinstall on
the vehicle at the first opportunity.
Limited Use Spare — If Equipped
The limited use spare tire is for temporary
emergency use only. This tire is identified by
a label located on the limited use spare
wheel. This label contains the driving limita-
tions for this spare. This tire may look like the
original equipped tire on the front or rear axle
of your vehicle, but it is not. Installation ofthis limited use spare tire affects vehicle
handling. Since it is not the same as your
original equipment tire, replace (or repair)
the original equipment tire and reinstall on
the vehicle at the first opportunity.
WARNING!
Limited use spares are for emergency use
only. Installation of this limited use spare
tire affects vehicle handling. With this tire,
do not drive more than the speed listed on
the limited use spare wheel. Keep inflated
to the cold tire inflation pressures listed on
your Tire and Loading Information Placard
located on the driver’s side B-Pillar or the
rear edge of the driver’s side door. Replace
(or repair) the original equipment tire at
the first opportunity and reinstall it on your
vehicle. Failure to do so could result in
loss of vehicle control.
Wheel And Wheel Trim Care
All wheels and wheel trim, especially alumi-
num and chrome plated wheels, should be
cleaned regularly using mild (neutral Ph)
soap and water to maintain their luster and to
SERVICING AND MAINTENANCE
236

prevent corrosion. Wash wheels with the
same soap solution recommended for the
body of the vehicle and remember to always
wash when the surfaces are not hot to the
touch.
Your wheels are susceptible to deterioration
caused by salt, sodium chloride, magnesium
chloride, calcium chloride, etc., and other
road chemicals used to melt ice or control
dust on dirt roads. Use a soft cloth or sponge
and mild soap to wipe away promptly. Do not
use harsh chemicals or a stiff brush. They can
damage the wheel’s protective coating that
helps keep them from corroding and
tarnishing.
CAUTION!
Avoid products or automatic car washes
that use acidic solutions or strong alkaline
additives or harsh brushes. Many aftermar-
ket wheel cleaners and automatic car
washes may damage the wheel's protective
finish. Such damage is not covered by the
New Vehicle Limited Warranty. Only car
wash soap is recommended.When cleaning extremely dirty wheels includ-
ing excessive brake dust, care must be taken
in the selection of tire and wheel cleaning
chemicals and equipment to prevent damage
to the wheels. Select a non-abrasive, non-
acidic cleaner for aluminum or chrome
wheels.
CAUTION!
Do not use scouring pads, steel wool, a
bristle brush, metal polishes or oven
cleaner. These products may damage the
wheel's protective finish. Such damage is
not covered by the New Vehicle Limited
Warranty. Only car wash soap is recom-
mended.
NOTE:
If you intend parking or storing your vehicle
for an extended period after cleaning the
wheels with wheel cleaner, drive your vehicle
and apply the brakes to remove the water
droplets from the brake components. This
activity will remove the red rust on the brake
rotors and prevent vehicle vibration when
braking.Dark Vapor Chrome, Black Satin Chrome, or Low
Gloss Clear Coat Wheels
CAUTION!
If your vehicle is equipped with these
specialty wheels, DO NOT USE wheel
cleaners, abrasives, or polishing com-
pounds. They will permanently damage
this finish and such damage is not covered
by the New Vehicle Limited Warranty.
HAND WASH ONLY USING MILD SOAP
AND WATER WITH A SOFT CLOTH. Used
on a regular basis; this is all that is re-
quired to maintain this finish.
Tire Chains (Traction Devices)
Use of traction devices require sufficient tire-
to-body clearance. Follow these recommen-
dations to guard against damage.
• Traction device must be of proper size for
the tire, as recommended by the traction
device manufacturer.
• Install on Rear Tires Only.
237

• Due to limited clearance, the following
traction devices are recommended:
• Original equipment 255/70R18 and
LT255/70R17 tire sizes are not chainable.
• The use of S-class snow chains is permitted
with the use of 245/75R17 tires on size 17
x 7.5 ET44.45 wheels.
WARNING!
Using tires of different size and type
(M+S, Snow) between front and rear axles
can cause unpredictable handling. You
could lose control and have a collision.
CAUTION!
To avoid damage to your vehicle or tires,
observe the following precautions:
• Because of restricted traction device
clearance between tires and other sus-
pension components, it is important
that only traction devices in good condi-
tion are used. Broken devices can cause
serious damage. Stop the vehicle imme-
diately if noise occurs that could indi-
CAUTION!
cate device breakage. Remove the dam-
aged parts of the device before further
use.
• Install device as tightly as possible and
then retighten after driving about ½ mile
(0.8 km).
• Do not exceed 30 mph (48 km/h).
• Drive cautiously and avoid severe turns
and large bumps, especially with a
loaded vehicle.
• Do not drive for a prolonged period on
dry pavement.
• Observe the traction device manufactur-
er’s instructions on the method of instal-
lation, operating speed, and conditions
for use. Always use the suggested oper-
ating speed of the device manufacturer’s
if it is less than 30 mph (48 km/h).
• Do not use traction devices on a com-
pact spare tire.
Tire Rotation Recommendations
The tires on the front and rear of your vehicle
operate at different loads and perform differ-
ent steering, handling, and braking func-
tions. For these reasons, they wear at unequal
rates.
These effects can be reduced by timely rota-
tion 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
maintain mud, snow, and wet traction levels,
and contribute to a smooth, quiet ride.
Refer to the “Maintenance Plan” for the
proper maintenance intervals. The reasons
for any rapid or unusual wear should be
corrected prior to rotation being performed.
The suggested rotation method is the
“rearward-cross” shown in the following
diagram.
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238