GMC 1982 Light Duty Truck Service Manual page 393

part in that they could affect the performance of vital components and
systems, an d/or could result in major repair expense. They must be replaced
with one of the same part number or with an equivalent part if replacement
becomes necessary. Do not use a replacement part of lesser quality or
substitute design. Torque values must be used as specified during reassembly
to assure proper retention of this part.
General D escription............................................................
Replacement T ire s ............................................................
Metric T ir e s ........................................................................
Replacement W h e e ls ........................................................
Certification L a b e l............................................................
Service O perations............................................................... 3E-2
Tire Inspection and R o ta tio n ........................................
GENERAL DESCRIPTION
The factory installed tires and wheels are designed to
operate satisfactorily with loads up to and including the full
rated load capacity when inflated to the recom m edned
inflation pressures.
Correct tire pressures and driving techniques have an
im p o rta n t influence on
excessively rapid acceleration, and unnecessary sharp
braking increase tire wear.
REPLACEMENT TIRES
CAUTION: Do not mix different types of tires on
the same vehicle such as radial, bias, and bias-
belted tires except in emergencies, because
vehicle handling may be seriously affected and
may result in loss of control.
Som e truck-type tires and most passenger-car-type
radial tires have a T P C Spec. No. (T ire Perform ance
C rite ria Specification N u m b e r ) molded into the tire
sidewall near the tire size marking. This shows that the tire
meets rigid size and performance standards which were
developed for the vehicle. The T P C Spec. No. assures a
proper combination of endurance, load capacity, handling,
and traction on wet, dry and snow covered surfaces. When
replacing tires with tires having the same TPC Spec. No.,
tires will be compatible with the vehicle. W hen replacing
tires with those not having a T P C spec, use the same size,
load range, and construction type (bias, bias-belted, or
radial) as the original tires on the vehicle (see the
Certification Label Fig. 3E-3). Use of any other size or type
tire m ay affect load carrying capacity, ride, handling,
sp ee d o m e te r/o d o m eter
clearance, and tire clearance to the body and chassis. If
replacing only a single tire, it should be paired on the same
axle with the least worn tire of the others.
All tires on four-wheel drive vehicles must be of equal
size (but not necessarily ply rating) and of same tread
configuration.
SECTION 3E
WHEELS AND TIRES
NOTICE: The Wheel bolt and nut fasteners are an important attaching
tire life. Heavy cornering,
calibration, vehicle ground
INDEX
Tire Inflation Pressure..................................................... 3E-3
3E-1
Correcting Irregular Tire W e a r .................................... 3E-4
3 E - 1
Wheel In sta lla tio n ............................................................ 3E-7
3E-1
Tire Mounting and D em ounting.................................. 3E-8
3E-1
Tire R epair.......................................................................... 3E-9
3E-2
Aluminum Wheel M ain tenan ce.................................... 3E-9
Wheel N u t T o rq u e s..........................................................3E-10
3E-3
Replace tires when:
1. Tires are worn to a point where 2 /3 2 inch (1.6
millimetres) or less tread remains, or the cord or fabric
is exposed. To help detect this, tires have built-in tread
wear indicators (Fig. 3E -4) that appear between the
tread grooves when the tread depth is 2 /3 2 inch
(1.6mm) or less. When the indicators appear in two or
more adjacent grooves at three spots around the tire,
the tire should be replaced.
2. Tire tread or sidewall is cracked, and, or snagged deep
enough to expose the cord or fabric.
3. Tire has a bump, bulge, or split.
4. Tire sustains a puncture, cut, or other injury that c an't
be correctly repaired because of the size or location of
the injury.
Metric tires are available in two load ranges, Standard
load and Extra load. Figure 3E-1 shows the meaning of the
metric tire format. Most metric tire sizes do not have exact
corresponding alpha tire sizes. For example, a P205/75R15
is not exactly equal in size and load carrying capacity to an
F R 7 8 -15. For this reason, replacement tires should be of the
same size, load range, and construction as those originally
on the car. If metric tires must be replaced with other sizes,
such as in the case of snow tires, a tire dealer should be
consulted. Tire companies can best recommend the closest
match of alpha to metric sizes within their own tire lines.
The m etric term for tire inflation pressure is the
Kilopascal (kPa). Tire pressure will usually be printed in
both kPa and psi. Metric tire gages are available from tool
suppliers. The chart (Fig. 3E-2) converts commonly-used
inflation pressures from kPa to psi.
REPLACEMENT WHEELS
Wheels must be replaced if they become dam aged (for
example: bent, heavily rusted, leak air) or if wheel nuts often
become loose. Do not use bent wheels which have been
straightened, and do not use inner tubes in leaking wheels
which are designed for tubeless tires. Such wheels may have
structural damage and could fail without warning.
WHEELS A N D TIRES
METRIC TIRES
3E-1