TIRE MAINTENANCE MANUAL - Goodyear Off-The-Road (OTR)

Fig. 14.This break resulted from a severe blow
while overinflated.
Fig. 15. Rapid air loss like this occurs
frequently when tires are overinflated and
suffer an impact.
Underinflation
An underinflated tire will deflect too much
leading to excessive sidewall flexing.
Underinflation typically results in:
• Irregular or uneven tread wear.
• Sidewall radial cracks.
• Ply separation.
• Loose or broken cords inside the
tire.
• Fabric carcass fatigue. (Fig. 16)
• Belt edge separation
Tires operated in soft soil or sand have
lower inflation recommendations. Tires operated
on paved or hard gravel surfaces
have higher inflation recommendations.
13
In soft soil, the tire makes an impression.
The impression cradles the tire and reduces
excess deflection. Inflation can be reduced.
Tires operated on hard surfaces do not receive
this support. They have to control
deflection by inflation pressure. Higher
pressures are required.
Indirect, but important, advantages of
lower inflation pressures include:
• Better flotation.
• Better traction.
• Better resistance to cutting and impact
breaks.
Fig. 16. Fig. 17.
Loose or broken cords can result from severe
underinflation.
Radial cracks indicate continuous underinflation
and/or overload operation. (Fig. 17)
Continuous operation results in heat
buildup in a tire. The hot air expands as a
result of the increase in temperature. The
tire’s carcass restricts this expansion so pressure
increases.
In normal off-the-road operation this does
not cause deterioration. The pressure becomes
stabilized when internal heating is
balanced by external cooling.