Chevrolet 70 1969 Series, Shop Manual

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WHEELS A N D TIRES 10-2
To check wheel nut torque on wheels which
are installed on a vehicle, it is necessary to first
loosen outer nuts before inner nuts can be checked.
D U A L W H E E L S
When installing dual wheels care should be
taken to position valve stems 180 degrees apart.
W H E E L STUDS O R B O L T S
If any wheel experiences a single stud failure
caused by a loose-running wheel all studs should be
replaced.
A loose running wheel may cause only one stud
to break, but several more studs may become
fatigued to the point of failure, but not actually
breaking. Replacing only the one broken stud and
remounting wheel will then set the stage for a
second and possibly more serious failure. If holes
in wheel have become elongated or enlarged, re­
place wheel.
C A U T IO N : Most truck "tire rim
accidents” are caused by carelessness,
thoughtlessness, or lack of experience.
Unless experienced, do not attempt to re­
pair tire. Have tire repairs made by a
reliable tire repair shop.
WHEEL INSPECTION (BUDD TYPE)
Do not use wheels with bent rims. 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 typical diagram
(fig. 4) for checking points.
1. Remove wheel from vehicle and dismount
tire.
2. Clean all rust, scale, dirt, and greasefrom
rim.
3. Mount wheel securely in a lathe or other
suitable fixture. N O T E : Face of hub in lathe or
fixture must run true, as any runout at that point
will be increased from 1-1/2 to 3 times at check­
ing points on rim.
4. Revolve wheel slowly and check at point
" A " for lateral runout (wobble). This should not
exceed 3 /3 2 ” . Check at point "B " for radial runout
(out-of-round). This should not exceed 3 /3 2 ” total
indicator reading. Wheels that are distorted in
excess of these limits should be replaced.
N O T E : Additional instructions on balancing
wheel and tire assemblies are included under
"Wheel and Tire Balancing” later in this section.
TIRES
Tube type tires are standard and optional on
all vehicles covered in this manual.
One of the most important factors of econom­
ical and safe truck operation is systematic and
correct tire maintenance. The tires must not only
support the weight of the loaded vehicle, but they
are also integral parts of the transmission and
braking system. Therefore, the tires used on all
trucks should receive the same amount of careful,
systematic, and regular maintenance as do other
operating units.
The three major causes of tire troubles are
(1) underinflation, (2) bruises, and (3) misalign­
ment. Tires should be checked periodically to pre­
vent excessive damage caused by these conditions.
INFLATION OF TIRES
Underinflation is the greatest cause for loss
of tire life expectancy. Tires should be checked
frequently for this condition. The fabric, rubber,
bead, contour, and size of tires used on these ve­
hicles are designed to obtain maximum length of
service under all operating conditions to which
vehicles may be subjected. TIRES A R E D ESIG N ED
T O O P E R A T E E F F IC IE N T L Y O N L Y O N A PR E­
SCRIBED A M O U N T O F AIR. Unless the correct air
pressure is consistently maintained, the tires will
not function as they should; consequently, safe
economical operation of vehicle will be materially
affected.
An underinflated tire runs sluggishly, heats
up quickly because of the greater flexing, and is
subjected to more frequent bruising. On the other
hand, overinflation may weaken the tire, causing
a blow-out. In addition to the deteriorating effect
improperly inflated tires may have on the tire life,
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P MANUAL