Lesson 3/Learning Event 2
One of the decisions in tire inspection is when to remove the tire for recapping. Do not
permit the tire to remain on the vehicle too long, or all of the rubber will be worn from
the tire and the fabric will be exposed. When worn to the fabric, it is not practical to
repair the tire or apply new tread. Yet, if the tire is removed too soon, rubber will be
wasted since all of the possible use has not been attained from the tire.
On the nondirectional mud and snow tires on tactical vehicles, the tires should be
removed for recapping when the center of the tread is worn smooth. At this time the
ridges formed by the grooves of the tread are worn off at the tire center.
On commercial-type treads, the tread gage issued with the organizational tool set may be
used to check depth. Normally, the tread should not be less than 1/16 inch.
Some of the causes of rapid tire wear are misaligned wheels, excessive speed, improper
loading, grabbing brakes, and improper vehicle operation. A tire will normally wear with
a smooth surface, but when forced to slide or drag on the road, the surface becomes rough
and scuffed. Operating a vehicle in front-wheel drive more than required can also
increase tire wear. During the winter when tire chains are in use, improper installation or
use of chains can chew pieces out of the tires. When installed on the wheel, sharp edges
of tire chains should face away from the tire.
If the tire has been driven on too long while not wearing evenly, it may be damaged
beyond repair. Once the wear has extended into the fabric of the plies, it is unlikely the
tire can be repaired. Uneven wear can be caused by improper air pressure, incorrect
steering adjustments, faulty brakes, bad shock absorbers, loose wheel bearings, and poor
driving by the operators.
Front tires on a vehicle with too much toe-in will wear the outer edges at a fast rate. If
the front tires toe-out when the vehicle is traveling straight ahead, the tires will wear
rapidly on the inner edges. Improper toe-in or toe-out forces the tires to slide or drag
sideways as they roll over the road surface. A sharp featheredge is left on the edges of
the tire treads because of the sliding motion.
Too much free play in the steering linkages, loose wheel mountings, or loose wheel
bearings can also cause uneven wear on the front tires. Brake shoes that grab on any of
the wheels of a vehicle will cause the tire to slide and wear unevenly.