Abnormal Tire Wear; Adjusting Inflation Pressures - Jeep 1979 CJ-5 Technical & Service Manual

WHEELS AND TIRES 2H-3
When sustained high speed operation is anticipated,
tires may be inflated to recommended full load inflation
pressures plus an additional 2 psi (14 kPa). However,
inflation pressures must not exceed maximum'recom-
mended pressures.
Tire pressures should be checked and adjusted to rec-
ommended levels on a weekly basis. This is especially
important when extreme changes of 20 degrees or more
in average seasonal temperatures occur and is especially
important on vehicles with Quadra-Trac.
Adjusting Inflation Pressures
Check and adjust inflation pressures only when the
tires are cold, or driven for less than two miles at speeds
below 40 mph (64 km/h), or after the vehicle has been
parked for three hours or more.
Do not reduce inflation pressures if the tires are hot,
or driven over two miles at speeds above 40 mph (64
km/h). At this stage, tire pressures may increase as
much as 6 psi over cold inflation pressures due to air
expansion caused by heat buildup in the tire.
When checking and adjusting inflation pressures, al-
ways use a reliable and accurate gauge to ensure proper
inflation levels.
ADNORKAL TIRE 1EAR
Abnormal tire wear may be caused by incorrect in-
flation pressures, tire-wheel unbalance, worn suspen-
sion components, improper brake operation, bent
wheels, front wheel alignment, and excessive speed on
turns.
In most cases, inspection of tire wear patterns will
reveal the cause of abnormal wear. The various types of
wear patterns and necessary corrective action are illus-
traed in Figure 2H-3.
Rapid wear of the tread shoulders is usually caused by
underinflation or lack of rotation or a combination of
both. If this type of wear occurs and the tires are serv-
iceable, rotate the tires and inflate them to recom-
mended levels when they are cool.
Rapid wear at the tread center is usually caused by
overinflation or lack of rotation or a combination of
both. If this type of wear occurs and the tires are still
serviceable, rotate the tires and inflate them to recom-
mended levels when they are cool.
Cracked treads are usually caused by underinflation
or excessive high speed operation or a combination of
both. Tires with cracked treads should be replaced and
the replacement tires properly maintained to avoid a
recurrence.
Excessive wear of one tread shoulder may be caused
by excessive speed on turns or by incorrect camber.
Incorrect negative camber will wear the inboard tire
shoulder while incorrect positive will wear the outboard
shoulder. If this type of wear occurs, check camber. If
camber is incorrect, the front axle housing may need to
be replaced. If camber is within specified limits, caution
the owner about excessive speed on turns. If the tires are
serviceable, rotate them and adjust inflation pressures
to recommended levels.
Incorrect toe-in will cause the tire tread surface to
develop a feathered edge. One side of the tread will be
rounded while the opposite side develops a feathered
edge. This type of wear indicates that the tire is side
slipping and scuffing as it moves over the road surface.
A feathered edge that faces toward the vehicle in-
dicates excessive toe-in. A feathered edge that faces
away from the vehicle indicates excessive toe-out. The
direction in which a feathered edge has developed can be
determined by passing a hand over the tire tread sur-
face. Bent steering knuckle arms can also cause this type
of wear.
If a feathered edge develops, check and correct toe-in
as necessary and rotate the tires if they are serviceable.
Fig. 2H-3 Tire Wear Patterns