vehicle. They provide the best overall performance
for normal operation. The ride and handling charac-
teristics match the vehicle’s requirements. With
proper care they will give excellent reliability, trac-
tion, skid resistance, and tread life.

Driving habits have more effect on tire life than

any other factor. Careful drivers will obtain, in most
cases, much greater mileage than severe use or care-
less drivers. A few of the driving habits which will
shorten the life of any tire are:

• Rapid acceleration

• Severe application of brakes

• High-speed driving

• Taking turns at excessive speeds

• Striking curbs and other obstacles

• Operating vehicle with over or under inflated

tire pressures

Radial ply tires are more prone to irregular tread

wear. It is important to follow the tire rotation inter-
val shown in the section on Tire Rotation. This will
help to achieve a greater tread-life potential.

TIRE IDENTIFICATION

Tire type, size, aspect ratio and speed rating are

encoded in the letters and numbers imprinted on the
side wall of the tire. Refer to the chart to decipher
the tire identification code (Fig. 1).

Performance tires will have a speed rating letter

after the aspect ratio number. For example, the letter
“S” indicates that the tire is speed rated up to 112
mph (180 km/h). The speed rating is not always
printed on the tire sidewall.

• Q -up to 100 mph (160 km/h)

• T -up to 118 mph (190 km/h)

• U -up to 124 mph (200 km/h)

• H -up to 130 mph (210 km/h)

• V -up to 149 mph (240 km/h)

• Z -more than 149 mph (240 km/h) (consult the

tire manufacturer for the specific speed rating)

TIRES AND WHEELS

22 - 1

An All Season type tire will have either M + S, M

& S or M-S (indicating mud and snow traction)
imprinted on the side wall.

TIRE CHAINS

Refer to the owners manual supplied with the vehi-

cle to determine whether the use of tire chains is per-
mitted on this vehicle.

RADIAL-PLY TIRES

DESCRIPTION

Radial-ply tires improve handling, tread life and

ride quality, and decrease rolling resistance.

Radial-ply tires must always be used in sets of

four. Under no circumstances should they be used on
the front only. They may be mixed with temporary
spare tires when necessary. A maximum speed of 50
MPH is recommended while a temporary spare is in
use.

Radial-ply tires have the same load-carrying capac-

ity as other types of tires of the same size. They also
use the same recommended inflation pressures.

The use of oversized tires, either in the front or

rear of the vehicle, can cause vehicle drive train fail-
ure. This could also cause inaccurate wheel speed
signals when the vehicle is equipped with Anti-Lock
Brakes.

The use of tires from different manufactures on the

same vehicle is NOT recommended. The proper tire
pressure should be maintained on all four tires.

SPARE TIRE–TEMPORARY

DESCRIPTION

The temporary spare tire is designed for emer-

gency use only. The original tire should be repaired
or replaced at the first opportunity, then reinstalled.
Do not exceed speeds of 50 M. P. H. when using the
temporary spare tire. Refer to Owner’s Manual for
complete details.

REPLACEMENT TIRES

DESCRIPTION

The original equipment tires provide a proper bal-

ance of many characteristics such as:

• Ride

• Noise

• Handling

• Durability

• Tread life

• Traction

• Rolling resistance

• Speed capability
It is recommended that tires equivalent to the orig-

inal equipment tires be used when replacement is
needed.

Failure to use equivalent replacement tires may

adversely affect the safety and handling of the vehi-
cle.

The use of oversize tires may cause interference

with vehicle components. Under extremes of suspen-
sion and steering travel, interference with vehicle
components may cause tire damage.

WARNING: FAILURE TO EQUIP THE VEHICLE WITH
TIRES HAVING ADEQUATE SPEED CAPABILITY
CAN RESULT IN SUDDEN TIRE FAILURE.

DIAGNOSIS AND TESTING

PRESSURE GAUGES

A quality air pressure gauge is recommended to

check tire pressure. After checking the air pressure,
replace valve cap finger tight.

TREAD WEAR INDICATORS

Tread wear indicators are molded into the bottom

of the tread grooves. When tread depth is 1.6 mm
(1/16 in.), the tread wear indicators will appear as a
13 mm (1/2 in.) band (Fig. 2).

Fig. 1 Tire Identification

22 - 2

TIRES AND WHEELS

DESCRIPTION AND OPERATION (Continued)

Tire replacement is necessary when indicators

appear in two or more grooves or if localized balding
occurs.

TIRE WEAR PATTERNS

Under inflation will cause wear on the shoulders of

tire. Over inflation will cause wear at the center of
tire.

Excessive camber causes the tire to run at an

angle to the road. One side of tread is then worn
more than the other (Fig. 3).

Excessive toe-in or toe-out causes wear on the

tread edges and a feathered effect across the tread
(Fig. 3).

TIRE NOISE OR VIBRATION

Radial-ply tires are sensitive to force impulses

caused

improper

mounting,

vibration,

wheel

defects, or possibly tire imbalance.

To find out if tires are causing the noise or vibra-

tion, drive the vehicle over a smooth road at varying
speeds. Note the noise level during acceleration and
deceleration. The engine, differential and exhaust
noises will change as speed varies, while the tire
noise will usually remain constant.

VEHICLE LEAD DIAGNOSIS AND CORRECTION

Use the following chart to diagnose and correct a

vehicle leading or drifting condition.

Fig. 3 Tire Wear Patterns

Fig. 2 Tread Wear Indicators

1 – TREAD ACCEPTABLE
2 – TREAD UNACCEPTABLE
3 – WEAR INDICATOR

TIRES AND WHEELS

22 - 3

DIAGNOSIS AND TESTING (Continued)

VEHICLE LEAD DIAGNOSIS AND CORRECTION CHART

22 - 4

TIRES AND WHEELS

DIAGNOSIS AND TESTING (Continued)

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