TRUCK SERVICE MANUAL
WHEELS, RIMS, TIRES
NOTE: Some tire repair methods for simple
punctures do not require the dismounting of tire from rim.
Excessive speed is definitely one of the most
These methods should be regarded as temporary fixes
important factors in loss of tire mileage. The chart (Fig.
since there is a good chance of ply separation and
13) illustrates how an increase in speed from 40 to 50
ultimate tire failure can result when puncture plug is
mph results in 18% loss in mileage. An increase of speed
installed from the outside.
from 40 to 60 mph results in a 33% mileage loss.
1. Remove tire and wheel assembly and inflate the
tire to the recommended pressure. Locate the
leak and mark with a crayon. It may be
necessary to immerse the tire in water or apply a
coat of soapsuds to the tire to locate the leak.
Demount the tire. Probe the injury with an awl
(Fig. 14) to remove the puncturing object and
Fig. 13 Speed vs. Mileage
TIRE MATCHING (Dual Tires)
Use care in matching dual tires. Tires which
differ more than 1/4" in diameter or 3/4" in circumference
should not be mounted on the same dual wheel. Should it
become necessary to mount two tires of unequal size on
the same dual wheel, place the larger or less worn tire on
When mounting tires on tendem drive axles,
follow the same instructions as specified for dual tires.
However, never install the (four largest tires on one
driving axle and the four smallest on the other. This
method of tire mounting will cause high lubricant
temperatures which may lead to premature axle failures.
Methods for repairing tires will vary slightly with
2. Thoroughly clean the inside of the tire around the
each manufacturer and it is recommended that the tire
injury with rubber solvent and allow to dry. As a safety
manufacturers' procedures be followed if possible.
precaution, solvent vapors should be blown out of the tire
However, the procedure outlined here applies in general
with compressed air. Solvent is not needed
to most tires whether they are light duty or heavy duty.
Patching will usually be satisfactory for all injuries up to
3/16" diameter. Larger injuries should be handled by spot
or section repair methods. The first four steps given here
apply to both the hot and cold patch methods.