CHAPTER 2. CARE, MAINTENANCE, AND INSPECTION (Con't)
SECTION I. GENERAL INFORMATION (Con't)
2-7. TUBE AND FLAP USAGE (Con't).
f. Never use a tube in tubeless tire/rim assembly where the rim is suspected of leaking. Tubeless
tire/rim assemblies are designed to operate at a certain temperature without a tube. Adding a tube to this
assembly adds more mass, which can generate more heat in the tire cavity, resulting in tire or rim failure.
Also a tube in tubeless rim assembly may mask a potential problem with fatigue cracks or other fractures
in the rim assembly which otherwise would be noticed by a slow leaking tire. Continued use may cause
the rim to burst suddenly and with explosive force.
2-8. EXTREME COLD WEATHER CONDITIONS.
a. If vehicles are allowed to rest directly on ice, snow, or frozen mud for long periods of time, initial
thawing may occur and subsequently the tire will freeze in. The best way to keep tires from freezing to the
ground is to park the vehicle on a hard surface or any other available material, such as planks, logs,
flagstones, etc. The vehicle must be moved periodically to rotate the tires approximately 180°.
b. Synthetic tubes become brittle when temperatures drop below -40°F (-40
C) and will fail faster
than natural rubber tubes. To minimize the effect of low temperatures, lubricate the inside of tire, tube,
flap, bead, bead lock, and the rim portion exposed to the tire with tire and rim lubricant (Items 90-92,
Appendix C) instead of talcum and increase tire pressure by 10 percent.
2-9. VALVE POSITIONING.
For speed and convenience during inflation, valve stems should be readily accessible. They should be
properly centered in valve holes to prevent scraping against the brakedrums. They should be placed so that
valve stems extend through the wheels. Valve stems of inside duels should point away from the vehicle,
and valve stems of outside duels should point toward the vehicle. On dual wheels, the valve stem of the
outside wheel will be placed 180° apart from the valve stem of the inside wheel. With this arrangement,
locating the valve stem of the inside wheel is made simple. Spare tires should also be mounted on the
vehicle so that the valve stem is easily accessible. Every valve stem should be equipped with a valve cap
2-10. MARKING OF TIRES.
Using paint to mark tires in order to reduce pilferage is not recommended. A yellow label (Item 101,
Appendix C) marked US GOVT will be used. Installation procedures are contained in each kit.
2-11. MATCHING OF TIRES.
a. For longer tire life and more efficient performance, dual tires and tires on all-wheel drive vehicles
should be the same size, tread design, and tread wear. Improperly matched tires cause rapid, uneven wear.
They can also cause transfer case and differential failures.
b. Accurate matching of tires is necessary because tires on all-axle drive vehicles rotate at the same
speed when all axles are engaged. Dual wheels, because they rotate as a unit, must have their tire sizes
matched. It is for this reason that all drive wheels must have tires of the same circumference and diameter.
If one tire of a pair of dual tires is worn considerably more than the other, it will not carry its proper share
of the load which will result in uneven wear of the smaller tire. The large tire will have irregular wear due
to increased load.
c. Never mix radial ply tires with bias or belted tires. Mixing bias and belted bias tires on the same
vehicle should also be avoided. Snow tires should be of the same size and type of construction as the front
tires. The problems encountered when mixing tire sizes and types on a vehicle are loss of steering control,
inadequate vehicle handling, and potential mechanical damage. These problems will vary depending on
the stability of the tires used, differences in dimension, differences in air pressure, and other operating
conditions. New or practically new dual tires of the same make, size, tread type, and tread wear may be
matched without measuring the circumference or the diameter.