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6-10
TROUBLE DIAGNOSIS
CHASSIS SUSPENSION
(2
08)
SECTION 6-B
TROUBLE DIAGNOSIS-CHASSIS SUSPENSION
CONTENTS OF SECTION 6
-8
Paragraph
Subject
Page
6-9
Abnorm a l T
ire W
ear .
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.
6-1
0
6-10
Faulty
Springs or Shock
Absorbers
. .
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.
.
.
. . . .
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.
. .
. .
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6-
13
Parag
raph
Subject
Page
6-11
Improper Steering Action.
.
. .
.
.
6-14
6-12
Car
Rough ness
or Vibration
.. .
.
6-15
Bulletin
Na
.
Page
No.
SERVICE BULLETIN REFERENCE
SUBJECT
.
6
- 9
ABNORMAL TIRE WEAR
a.
General
Ope ratin g
Cond iti ons
Assuming that there is no
misalignment
con-
dition to cause unnatural wear, the life of tires
depends largely
upon
car operating
conditions
and driving
habits.
Tires wear at a much faster rate in some
localities
than in others
because
of road and
operating conditions. Some types of roads are
much more
abrasive
than others.
Tire wear
is
also dependent upon the number of hills and
mountains whicli the car
must
go up and down,
the severity of grades, the number of starts
and stops, driving speeds, the amount of rain
and snow, and prevailing temperatures. Tire
wear increases rapidly with both speed and
temperature. Tires used at low speeds or in
cool climates will have longer life than tires
used for high speed driving in hot climates.
Driving habits have a very important bear-
ing on tire
life.
A careful driver may obtain
much greater mileage from a set of tires than
would be obtained by a severe or careless
driver. Rapid acceleration
a
nd
deceleration,
se-
vere application of brakes,
taking
turns at ex-
cessive speed, high speed
driving,
and striking
curbs or other obstructions which lead to mis-
alignment are driving habits which will shorten
the life of any tire.
Maintenance of proper inflation pressure and
periodic interchanging of tires to equalize wear
are within the control of the
driver.
Underin-
flation raises the internal temperature of a tire
greatly, due to the continual friction caused by
the flexing
of
the side walls. Tires squealing on
turns is an indication of underinflation or of
excessive speed on the turns. A combination of
underinflation, high road
temperatures,
and
high speed driving will quickly ruin the best
tire made.
High speed on straight highways causes
more
rapid wear on the rear than on the front t
ires,
and driving turns and curves at too high a
rate
of speed causes the front tires to wear much
faster than the rear tires.
An inspection of the
tires, together
with in-
formation as to locality in which the car has
been operated will usually
indicate whether
ab-
normal wear is due to the
operating
conditions
described above, or to mechanical faults which
should be
corrected.
The various types of abnormal tire wear and
their causes are described in the foll
owing
sub-
paragraphs.
b. Shoulder or
Underinfla t ion
Tr ea d Wear
When
a tire is underinflated,
the side
walls
and sh
oulders
of the tread ca r r y
the load
while
the center of tread folds in or compr esses du
e
to the low
internal
air
pressure. This
action
ca uses
the
shoulders to take all of
the driving
and braking load
,
re
sulting
in mu
ch
faster
wear of shoulders than of the center of
tread.
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