GMC 4000 Series Service Manual page 519

Sec. 10
Page 508
WHEELS A N D TIRES
2. Starting at bottom, tighten#l nut 15-20foot­
pounds.
3. Tighten nuts 2, 3, 4, and 5 to 190-210 foot­
pounds, in this sequence.
4. Retorque nut #1 to 190-210 foot-pounds.
This torquing sequence will give proper torque
with minimum wheel run-out. Maximum p erm iss­
ible wheel run-out is 1/8-inch.
WHEEL INSPECTION
Do not use wheels with bent rim s. The con­
tinued use of such wheels will result in excessive
tire wear and, if wheel is mounted on front of ve­
hicle, difficulty in steering will be experienced.
Wheels that are thought to be distorted may be
checked as follows, referring to figure 4 for check­
ing points:
1. Raise axle at side to be checked and safely
support underneath.
2. Tool for checking run-out may be readily
improvised as follows: secure block of wood ap­
proximately 6" x 6" x 14" or material with suit­
able base so it w ill remain positioned. Secure
thin piece of wood or suitable material 10" long
such as ruler or yardstick, and fasten to wood
block to a height in relation to rim surfaces as
shown in figure 4. Tighten screw sufficiently so
pointer will hold its position when adjusted.
3. Position pointer at crown of rim (A, fig. 4).
Slowly revolve wheel and move pointer toward wheel
until it contacts wheel at nearest point.
4. Continue to revolve wheel and check amount
of lateral run-out (amount of wheel side wobble).
G M C S E R V I C E M A N U A L
Figure 3 — W heel N ut Tightening Sequence for Cast W heels
This should not exceed 3/32-inch.
point (B, fig. 4). Follow the above procedure to
check radial run-out (out-of-round condition); this
should not exceed 3/32-inch. If wheel is distorted
beyond these dimensions it should be replaced.
distorted, hub may be checked as follows: Replace
the existing wheel with a wheel known to be true.
Revolve the wheel and make the previously men­
tioned tests. If tests are within lim its, the hub is
satisfactory, but wheel is sprung.
side wobble by placing a straight-edge on face or
hub of wheel. Measure distance from straight-edge
to edge of wheel rim, this should be checked at
four equally spaced locations. If distance is the
same at all positions wheel is not distorted (see
fig. 5). A dismounted wheel may also be checked
for radial, and lateral run-out if desired, by temp­
orarily mounting it to a hub on vehicle. Follow the
previous Steps 2, 3, 4, and 5.
all vehicles covered in this manual.
omical and safe truck operation is system atic
and correct tire maintenance. The tires must not
only support the weight of the loaded vehicle, but
they also serve to transmit driving and braking
forces to road surface. Therefore, the tires used
5. Place point of marker at inside of wheel at
6. If doubt exists whether the wheel or hub is
7. A dismounted wheel may be checked for
TIRES
Tube-type tires are standard and optional on
One of the most important factors of econ­