Optimum inflation pressure is one of the most important aspects of caring for tires. Proper inflation pressure maintains an even ground contact pressure of the tire tread and prevents uneven wear. In addition, by reducing rolling resistance and quickly discharging any heat that is generated, internal heat levels are kept at a stable level. In sum, the right inflation pressure delivers maximum performance in terms of safe driving, riding comfort and monetary savings.
The optimum tire inflation pressure is indicated on a vehicle placard. If a placard is not available, some manufacturers list the original tire pressure in the vehicle owner’s manual. Tire suppliers can also provide relevant information. In addition, the maximum inflation pressure for safe driving is marked on the tire sidewall.
Generally, the optimum inflation pressure is about 90% of the maximum level. For high-speed driving, drivers are recommended to use a higher than normal pressure.
Higher inflated tires cannot isolate road irregularities well and this leads to a harsher ride.
Tires can also be damaged more easily, lowering safety levels.
- Safety - More susceptible to damage from external factors (potholes, debris)
- Economy - Speeds up wear, in particular wear of central tread part
Underinflation increases tire wear, creates excessive heat and causes the sidewalls to overflex. This diminishes the tires' integrity, making them vulnerable to premature failure.
- Excessive heat leads to separation or cord failure
- Easier for tire beads to separate from wheel
- Excessive friction between wheel and tire beads can lead to bead failure
- Susceptible to standing wave deformation
- Speeds up wear, in particular wear of shoulder part
- Greater rolling resistance lowers a vehicle’s fuel economy
- Correct inflation pressure
- Maximum grip levels ensure best
pulling and braking performances.
Tire life span is extended through
- OverinflationVulnerable to external shocks,
cause of uneven wear
- Sidewall flexes more, causing
heat to build up and damage tires.
Cause of uneven wear
- Inflation pressure must be adjusted to load.
Follow inflation pressure recommendations issued by the automaker. If there are no guidelines from the car maker, tire manufacturers can supply the information.
- Air pressure can naturally decrease over use so regular checks should be made.The best time for checking air pressure is before long distance driving or at least once a week.
- Due to casing deflection, all tires generate heat and higher inflation pressure during operations which return to original levels after cooling. The rise in pressure during driving is normal and therefore should not be ‘bleeded’- reducing pressure in tires which have warmed up which results in an increase in pressure above their starting pressure. If air is let out in this state, underinflation can result, causing CBU(Cord Broken Up or Seperation). Air pressure must be measured in a ‘cold’ state. Driving just 2km can increase inflation pressure by about 4psi, so when adjusting pressure in a ‘hot’ state, add about 4psi over the recommended pressure in a cold state.
- Raising air pressure (0.2~0.3kg/cm2) for high-speed driving can prevent against the most dangerous state of standing wave phenomenon and irregular flexing. The higher air pressure reduces tire wrinkles and therefore results in lower tire temperatures while more effectively channeling water away on wet surfaces. In the case of dual wheels, both tires must have identical inflation pressures.
- Air leaks through faulty valves are relatively common. With a tubeless tire, most of the air leaks occur in the area joining the wheel and valve. Checks must be made using soapy water or other means to determine there are no air leaks around the valve area or in the area joining the wheel and tire.