TIRE DIAGNOSIS
IRREGULAR AND/OR PREMATURE WEAR
Irregular and premature wear has many causes. Some of them are:
incorrect inflation pressures, lack of tire rotation, driving habits, im-
proper alignment.
If the following conditions are noted, rotation is necessary:
1) Front tire wear is different from rear.
2) Uneven wear exists across the tread of any tire.
3) Front tire wear is unequal between the right and left.
4) Rear tire wear is unequal between the right and left.
5) There is cupping, flat spotting, etc.
A wheel alignment check is necessary if following conditions are
noted:
1) Front tire wear is unequal between the right and left.
2) Wear is uneven across the tread of any front tire.
3) Front tire treads have scuffed appearance with “feather” edges
on one side of tread ribs or blocks.
Hard Cornering
Under Inflation
Lack of Tire Rotation
Incorrect Wheel Alignment
Tire Construction not Uniform
Wheel Heavy Acceleration
WEAR INDICATORS
Original equipment tires have built-in tread wear indicators to show
when they need replacement.
These indicators will appear as 12 mm (0.47 in) wide bands when
the tire tread depth becomes 1.6 mm (0.063 in).
When the indicators appear in 3 or more grooves at 6 locations, tire
replacement is recommended.
TIRE WADDLE
Waddle is side to side movement at the front and/or rear of the ve-
hicle. It is caused by the steel belt not being straight within the tire.
It is most noticeable at a low speed, 5 to 30 mph.
It is possible to locate the faulty tire by road testing the vehicle. If
it is on the rear, the rear end of the vehicle shakes from side to side
or “waddles”. To the driver in his seat, it feels as though someone
is pushing on the side of vehicle.
If the faulty tire is on the front, waddling is more visual. The front
sheet metal appears to be moving back and forth and the driver
feels as though he is at the pivot point in vehicle.
Waddle can be quickly diagnosed by using Tire Problem Detector
(TPD) and following the equipment manufacture’s recommenda-
tions.
If TPD is not available, an alternative method of substituting known
good tire/wheel assemblies can be used as follows, although it
takes a longer time.
3-6
STEERING, SUSPENSION, WHEELS AND TIRES
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Страница 644: ...Prepared by Overseas Service Department 1st Ed October 1999 Printing 646 ...