Chevrolet 1980 Light Duty Truck Service Manual page 21

SERIES DESCRIPTION
K10 7/16" BO LTS (6)
C10, G10, G20 1/2" BO LTS (5)
AND P10
C20, K20, C30, G30,
P20 AND P30 9/16" BO LTS (8)
SINGLE W H EELS
C30, K30, G30
9/1 6 " BO LTS (8)
AND P30
DUAL W HEELS
HEAVY DUTY
W HEELS
5/8" BO LTS (10)
Fig. 0B-12--W heel Nut Torque
or disc mounting surface by scraping and
w ire brushing. Installing wheel w itho u t
good metal-to-metal
mounting surfaces can cause the wheel
nuts to loosen, w hich can later allow a
wheel to come off w hile the vehicle is
moving, possibly causing loss of control.
Dual Tire Operation
The outer tire of a pair on dual wheel installations
generally wears faster than the inner tire, if this occurs,
reverse position of the tires to equalize wear and achieve
optimum tire life.
In addition, when trucks are driven continuously on
high crown roads, an increase in air pressure of from 5 psi
(35 kPa) to 10 psi (70 kPa) in the outside tire of each dual
produces maximum tire life. Be sure not to exceed the
inflation pressure limits shown in the Load and Inflation
Charts in Section 3E.
W heel Nut Torque (Fig. OB-12)
Caution:
Trucks With Single Wheels:
As soon as possible a fte r installing a wheel-
and at the intervals shown on the chart in the
M aintenance Schedule
nuts with a torque wrench to the correct torque listed on
the chart which follows.
Trucks With Dual Wheels:
Have a mechanic tighten wheel nuts w ith a
torque w rench as stated above for single wheels
for both front and rear wheels.
truck, or wheel, or fasteners are new, also have the torque
set at the first 100, 1,000, and 6,000 miles (160, 1 600, and
9 600 km). This precaution is necessary because the
clamping system used on this type of wheel in some cases
needs to seat before the fasteners will hold a uniform clamp
load and remain fully tightened.
For both single and dual wheels, wheel nuts should be
tightened alternately and evenly to the correct torque in the
sequence shown in Section 3E. Never use oil or grease on
studs or nuts. Improperly tightened wheel nuts could
eventually allow the wheel to come off while the vehicle is
moving, possibly causing loss of control.
TORQUE
70-90 FT. LBS.
95-120 N .m
75-100 FT. LBS.
100-140 N .m
90-120 FT. LBS.
120-160 N .m
110-140 FT. LBS.
150-190 N .m
130-180 FT. LBS.
175-245 N .m
contact at the
have a mechanic tighten wheel
In addition , when the
M A IN TEN A N C E A N D LUBRICATION
CAUTION: This vehicle has some parts
dimensioned in the metric system as well
as in the customary
fasteners are metric and are very close in
dimension to w ell-known
fasteners in
Mism atched or incorrect fasteners can
result in damage to the vehicle or possibly
personal injury.
OB-13)
Inflation Pressure (Fig.
The cold inflation pressures for the factory installed
tires are on the label on the rear of the driver's door. The
tires must be inflated to these pressures to obtain the
GVWR (Gross Vehicle Weight Rating) or GAWR (Gross
Axle Weight Rating). Incorrect tire inflation pressures can
have adverse effects on tire life and vehicle performance.
Too low an air pressure causes increased tire flexing and
heat build-up. This weakens the tire and increases the
chance of damage or failure and can result in tire
overloading, abnormal tire wear, adverse vehicle handling,
and reduced fuel mileage. Too high an air pressure can
result in abnormal wear, harsh ride, and also increase the
chance of damage from road hazards.
Lower inflation pressures can be used for light truck-
type tires with reduced vehicle loads. After finding the load
on each tire by weighing the vehicle on a scale, the minimum
cold inflation pressures can be found in Section 3E.
Tire inflation pressures should be checked at least
monthly (including the spare if so equipped). Always check
tire inflation pressures when tires are "cold".
1. The "cold" tire inflation pressure applies to the tire
pressure when a vehicle has not been driven more than one
mile (1.6 km) after sitting for three hours or more.
2. It is normal for tire pressures to increase 4 to 8
pounds per square inch (30 to 60 kilopascals) or more, when
the tires become hot from driving.
reduce tire inflation pressures after driving vehicle. Bleeding
serves to reduce "cold" inflation pressure and increase tire
flexing which can result in tire damage and failure.
Passenger-Car-Type tires:
For sustained driving at speeds of 75 mph of
85 mph (1 2 0 k m /h to 140 km /h), in countries
w here such speeds are perm itted by law
inflation pressures must be increased 4 psi (30 kPa) above
the stated cold inflation pressures on the Certification Label,
when the 4 psi (30 kPa) adjustment would require pressures
greater than the maximum pressures stated for each load
OB-11
system. Some
customary
the inch system.
Do not "bleed" or
, cold
LIG H T D U TY T R U C K SER V IC E M AN UAL