Chevrolet DB90 Series, Руководство по обслуживанию

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S ec. 10-194
WHEELS AND TIRES
TIRE ROTATION
G enerally, it i s the b e st p ra ctice to "breakin"
new tir e s on front w h e e ls. "Breaking in" on an easy
p osition generally in c r e a s e s the o v era ll tir e life .
The m ovem ent of the tir e s from front to v a r ­
io u s rear w heel p o sitio n s depends upon the type of
unit being operated. It i s generally n e c e ssa r y to
u se tires! with good non-skid tread design on drive
w h e e ls. ;
T ire$ with le a s t tread design should be used
on tr a ile r w h eels, and particu larly on the re a r of
tandem w h eels. T his is due to th efa ctth a t cuts are
found m ore often on the tr a ile r and r e a r tandem
t ir e s and by using w ell worn tir e s on th ese w h eels,
l o s s on tir e s due to road hazards is m inim ized.
NOTE: When rotating any tir e , follow re co m ­
m endations in " selection of tir e s" a s covered p r e ­
viou sly.
TWO-AXLE TRUCK
T ir e s should be moved from front w h eels to
r ea r w h eels (fig. 12) after 1 /3 of the tread design
i s worn off. If th ere is uneven front w heel tire
w ear, rotate tir e s im m ediately and check v eh icle
for m echanical ir r e g u la r itie s. When tir e s are
m oved to the r ea r, follow recom m endations in
m atching them with other tir e s .
TRUCK WITH TANDEM AXLE DRIVE
Follow the sam e p ra ctice a s d escrib ed for
sin g le -d r iv e axle except tir e s m ust be rem oved
from the fronts at l e s s s e r v ic e in ord er to provide
8 tir e s for the rear w h eels instead of 4 for the
sin g le -a x le d riv e. Since th ere are 5 tir e s on each
sid e of the v eh icle (fig. 12) the front tir e s should
be m oved to the rear when 1 /5 of the tread design
is worn off. Then match tir e s on each w h eel as
already d escrib ed but with an additionalprecaution
- the sum of the circu m feren ces of the four tir e s
fo r the front of the tandem drive a x le s should equal
the sum of the circ u m feren ces of the four tir e s on
the rea r of the tandem a x le s . T his precaution is
n e c e ssa r y to prevent e x c e s s iv e w ear from slip p age.
If there is a third differential betw een the two drive
a x le s, this precaution is u n n ecessary.
TRACTOR AND SEMI-TRAILER
A fter 1 /5 of the tread design i s worn off, tir e s
should be m oved from the front to the in sid e or
outside driving w h eels (shown in figu re 13), the
p osition being determ ined by matching a s reco m ­
mended. L ater the tir e s should be m oved to the
tr a ile r w h eels. The p o ssib ility of injury from cuts,
b r u ise s, e tc ., is grea ter in the tr a ile r w heel p o s i­
tion. By follow ing this rotation plan with tir e s , end­
ing th eir s e r v ic e on tr a ile r w h eels, at le a s t the
g rea ter portion of the tir e s e r v ic e has been ob­
tained even if they a r e damaged.
TRACTOR WITH TANDEM AXLE DRIVE
WITH SEMI-TRAILER WITH TANDEM AXLE
Follow sa m e procedure a s above for tractor
and s e m i-tr a ile r with s in g le -a x le except tir e s m ust
be rem oved fro m the front w h eels at le s s s e r v ic e
in order to provide for 16 tir e s in stead of 8. Since
th ere a re 9 t ir e s on each sid e of the v eh icle, the
front tir e s should be m oved to the r e a r when 1/9
o f the tread design is worn off (fig. 13). Then match
tir e s on each w heel a s already d escrib ed but with
an additional precaution - the sum of the circu m ­
fe r e n c e s of the 4 tir e s for the front of the tandem
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT