Great Dane 42101401 - Manual (Page 20)

Running a tire under inflated can have serious conse-
quences in addition to reducing tread life. Heat buildup
can cause the tire body to deteriorate, resulting in sep-
aration of the tread from the body or belt ply. A soft tire
overdeflects, causing fatigue breaks in the body cords.
Continued overdeflection causes breaks in the body
cord construction, leading to sudden air loss.
Running duals with one tire flat or under inflated can
lead to intense heat buildup in the flat or low tire due to
external and internal friction – to the extent that the
casing might burst into flames. Also, one tire of a dual
running flat or low means the other is overloaded and
may fail.
OVER INFLATION can also cause serious damage to
a tire. Because a tire is more rigid when over inflated, it
does not absorb road shocks as well. This can lead to
body breaks when impacting a bump or chuckhole. It
can stress the rim, leading to rim failure. And over
inflated tires are more likely to cut, snag, and puncture.
PROPER MATCHING
AND SPACING OF DUALS
Mismatched dual tires force the larger diameter tire to
an overload condition, causing it to overdeflect and
overheat. The smaller diameter tire will lack complete
road contact and will wear faster and more irregularly.
Tread or ply separation, tire body breaks, and blowouts
can develop from mismatching duals.
Permissible diameter differences between a tire and its
dual mate having equal inflation pressure are:
1/4" for 8.25 cross section (tubeless 9-22.5)
and smaller sizes
1/2" for 9.00 cross section (tubeless 10-22.5)
and larger sizes
To determine the difference in diameter measure the
tires forty-eight hours after initial inflation with a steel
tape. Measurements on the trailer can be made by
string gauge, straight edge, tire caliper, or a large
square.
Proper spacing between duals is necessary to prevent
sidewall contact at the “six o’clock” position. Such con-
tact creates excessive heat which can destroy the tires.
TIRE BRANDING
Whenever possible, tire branding should be in the
branding panel on the sidewall of most truck tires. Use
extreme caution to prevent branding too deeply. The
ideal branding depth is 1/32", and in no case should it
exceed 1/16".
If no branding panel is on the tire, brand the sidewall
midway between the rim flange and the tire’s maximum
section width.
MIXING RADIAL AND BIAS-PLY TIRES
Radial tires and bias-ply tires differ considerably in
their cornering force characteristics and spring rates.
The best overall performance usually can be achieved
by using tires of the same size and construction on all
wheels. However, different types of tires can be used
in combination on tandem axle trailers and multiple-
axle trailers under certain conditions.
Never mix different tire sizes or tire construction on the
same axle. Bias or radial tires may be used on either
axle of two-axle trailers if the trailer has dual rear
wheels or is equipped with wide-base single tires.
TUBE AND FLAPS
FOR TUBE-TYPE RADIAL TIRES
Since the tube holds the air, the importance of the tube
in the satisfactory performance of the tire is obvious.
The flexing characteristics of a radial truck tire require
a special inner tube. Never use a tube that has not
been identified as being suitable for use with radial-ply
tires.
Both tubes and tires must be the same size. For
example, a 10.00R20 tube must be used with a
10.00R20 tire, and the tube must be for a radial tire.
When using flaps, use radial flaps. Radial flaps are
manufactured especially for radial truck tires. For
correct flap size, check the tire manufacturer’s specifi-
cations. Always check for the correct designation
before installing a flap in a radial truck tire.
Note: Always use new radial tubes and flaps when
mounting new tube-type radial tires.
Replace any tire that has fabric exposed through the
tread or sidewall, or that has less than 2/32" tread
depth.
DANGER Tires operated in a flat condition
may catch fire resulting in potential product and
property loss.
NOTICE: Over inflation cannot increase the
carrying capacity of a tire above its maximum
rated load.
18
NOTICE: Never brand in the critical sidewall
flexing area near the tire maximum section width
of a radial ply tire. Branding that is too deep or
in the wrong place on the tire can result in tire
failure. Consult the tire manufacturer for more
detailed instructions.