204-03-4
Wheels and Tyres
204-03-4
DIAGNOSIS AND TESTING
E1076 EN
07/2001 2002 Bantam
Wheels and Tyres
Inspection and Verification
To maximize tyre performance, inspect the tyres
for signs of incorrect inflation and uneven wear,
which may indicate a need for balancing, rotation
or front suspension alignment. Tyres should also
be checked frequently for cuts, stone bruises,
abrasions, blisters, and for objects that may have
become embedded in the tread. More frequent
inspections are recommended when rapid or
extreme temperature changes occur or when
road surfaces are rough or occasionally littered
with debris.
As a further visible check of tyre condition, tread
wear indicators are molded into the bottom of the
tread grooves. When these indicator bands are
exposed to the road surface, new tyres should be
installed.
Tyre Wear Diagnosis
New tyres should be installed if the wear indictors
are exposed or if there is severe shoulder wear.
Shoulder wear is usually caused by either
excessive camber or excessive toe on radial
tyres.
Sometimes incorrect rear toe settings or
damaged struts will cause severe `cupping' or
`scalloped' tyre wear on non-drive wheels.
Severely misadjusted rear toe will also cause
other unusual wear patterns.
Road Test
A tyre vibration diagnostic procedure always
begins with a road test. The road test and
customer interview (if available) will provide much
of the information needed to find the source of a
vibration.
During the road test, drive the vehicle on a road
that is smooth and free of undulations. If vibration
is apparent, note and record the following:
• The speed at which the vibration occurs.
• What type of vibration occurs in each speed
range.
- mechanical or audible
• How the vibration is affected by changes in
the following:
- engine torque
- vehicle speed
- engine speed
• Type of vibration – sensitivity: torque
sensitive, vehicle speed sensitive or engine
speed sensitive.
The following explanations help isolate the
source of the vibration.
Torque Sensitive
This means that the condition can be improved or
made worse by accelerating, decelerating,
coasting, maintaining a steady vehicle speed or
applying engine torque.
Vehicle Speed Sensitive
This means that the vibration always occurs at
the same vehicle speed and is not affected by
engine torque, engine speed or the transaxle
gear selected.
Engine Speed Sensitive
This means that the vibration occurs at varying
vehicle speeds when a different transaxle gear is
selected. Increasing or decreasing engine speed
with the transaxle in NEUTRAL or by stall testing
with the transaxle in gear can sometimes isolate
it. If the condition is engine speed sensitive, the
cause is probably not related to the tyres.
If the road test indicates that there is tyre whine,
but no shake or vibration, the noise originates
with the contact between the tyre and the road
surface.
A thumping noise usually means that the tyre has
flat or soft spots making a noise as they slap the
roadway. Tyre whine can be distinguished from
axle noise. Tyre whine remains the same over a
range of speeds.
