Sec. 10
P age 66
WHEELS A N D TIRES
TUBE BREAKS NEXT TO THE VALVE
Im proper inflation procedure may cause a c ir
cu m feren tial crack or tea r in the valve base at the
edge of the bridge w a sh er. Figure 14, View A shows
the p osition of b eads, flap and tube with 4 or 5 lbs.
inflation p r e s s u r e . The tube is fully rounded out
w ithin the tir e , but the p r e ssu r e is insufficient to
m ove the beads on wide b a se r im s. Depending upon
tir e s iz e and condition of the rim , from 20 to 40
lb s. p r e s s u r e is required to push the beads onto
the tapered bead s e a ts a s shown in figure 14, View
B .
F orced by th is high p r e ssu r e , the tube can
stretch only in the rim a rea . B ecau se the r e s is t
ance to stretch is g re a te st at the valve b ase, ten
sion th ere is often enough to crack the tube at edge
of the valve b a se.
T his can be avoided by proper inflation pro
cedure a s d escrib ed la ter in th is section.
TUBE INSTALLATION
1. In sert tube in tir e and inflate as shown in
fig u re 15, View 1. rounded out. U se approximately
1 lb. of air or l e s s .
2. U sing a brush or cloth swab, apply a solu
tion of neutral vegetab le o il soap in the area of the
t ir e bead s, including flap. Do not allow soap solu
tion to run down into tir e . Extra ply rated tire s
may require soap on the rim bead sea t area.
3. Mount tir e on rim , cen ter valve and pull it
through hole in rim and hold firm ly against the
rim . Hold in th is p osition w hile inflating until beads
a re p rop erly seated .
4. C om pletely d eflate by rem oving valve core
o r using deflating tool. T his is extrem ely im port
ant to prevent tube buckling.
5. R e-in fla te tube to recom m ended p ressu re
(fig. 15, View 2). R efer t o ’’Load and Inflation T able”
at end of th is sec tio n .
NOTE: U sed flap s may cau se tube failure UN
LESS mounted with the s iz e tir e and rim originally
u sed . When tube and flap are not properly lubri
cated and mounted, they w ill be stretched thin in
the tir e bead and rim region (fig. 15, View 3). This
w ill ca u se prem ature fa ilu re .
A lw ays clean r im s thoroughly to rem ove rust.
C ertain p recau tion s m ust be taken when mount
ing u sed fla p s, or damage to the tire and tube will
r e su lt.
New truck and bus flap s can be u sed with any
one of se v e r a l different tir e and rim s iz e s a s r e c
om m ended. But once u sed , the flap must be r e
mounted in the sam e s iz e tir e and on the sam e siz e
rim from which it w as rem oved. Always u se flap
of adequate width to prevent tube pinching.
A s a precaution again st flap failu re, mark the
t ir e and rim s iz e on the flap at the tim e of rem oval
- if in sp ection show s that it is not damaged and can
be u sed again. When the flap is again mounted, this
m arking p r o te c ts against the danger of m isu sin g
the flap with the wrong s iz e tir e and rim .
New flap s and tubes should be u sed after tir e
o r rim r e p a ir s. It is in exp en sive in su ran ce sin c e
sm a ll w ear sp ots and im p erfection s in tubes and
flap s a re hard to s e e . T his could prevent future
tir e fa ilu r e s .
TUBE RECOMMENDATIONS
1. Long life and high m ileage r e c e iv ed from
p resen t day tir e s exhaust the u sefu l s e r v ic e lif e of
tu b es. T h erefore, when a ca sin g is worn to the
point of being u nsafe, the tube gen erally is in the
sa m e condition and should be rep laced with a new
one.
2. If valve cap is lo s t, clean end of valve b e
fo r e applying a ir hose to p reven t dust and dirt
from being blown into the tube. Apply new cap.
3. When tubes a re inflated for in sp ection , they
should not be inflated to the point of ’’b alloon in g.”
When a tube is ’’b alloon ed ,’’ it thins out in the
stretch ed area, making the tube too la rg e in that
a rea and resu ltin g in folds or w rin k les when r e
mounted.
SPACER B A N D S
INSTALLATION PROCEDURE
1. Check the sp a cer band for con cen tricity,
and a ssu r e y o u r se lf that it has not been d istorted
or bent, or o th erw ise m ishandled in shipm ent.
2. Do not m ove v e h ic le s , w h eels, a x le s, or
a s s e m b lie s by ro llin g on s p a c e r s.
3. P la c e the in sid e rim over the c a st spoke
w heel a s far a s p o ssib le up to the mounting le v e l.
4. Push the sp a c er band o v er the ca st spoke
w heel with a co n sisten t p r e s s u r e on both s id e s .
Guard again st cocking. The band should fit snugly
to the spokes and against the in sid e rim gutter
edge. (At th is point, the con cen tricity can be ch eck
ed by turning the sp a cer band on the w heel.)
5. Apply outer rim clam p s. Tighten clam p nuts
evenly to the recom m ended range, 5 / 8 ” studs from
150-175 foot-pounds, and
%"
studs from 190-210
foot-pounds torque. Apply torque evenly by grad
ually tightening nuts in an alternating pattern a c r o s s
the diam eter of the w h eels.
6. Check to s e e that clam ps do not bottom out,
and be su re the rim edges co n sisten tly m eet the
sp a cer band ed ges.
7. R echeck torque after a sse m b ly is u sed in
s e r v ic e after 500 and 1,000 m ile s .
M O U N T IN G A N D D E M O U N T IN G R IM S
For proper p roced u res in mounting and de
mounting different type r im s, r e fe r to fig u res 16,
17, 18, 19, and 19a for applicable type.
