1. Home
    2. Tyre Inflation Pressure

Yokohama India - Tyre Inflation Pressure

Yokohama India - Tyre Inflation Pressure

Tyre Inflation Pressure

Air pressure decreases naturally
Tyre air pressure decreases naturally (little by little). It is generally accepted that air pressure in tyres on a passenger car decreases by 5–10% (10–20kPa) every month.

Graph:a loss of fuel consumption is around 2%

Tyre size:195/65R 15
Starting pressure:220kPa(100kPa=1.0kgf/cm2)

  • (A) Air pressure(kPa)
  • (B) Decreases by 10-20kPa a month
Impact of low air pressure on fuel consumption
According to material released by The Energy Conservation Center, Japan, fuel consumption increases by around 2% in urban zones and 4% in the suburbs when air pressure drops 50kPa (0.5kgf/cm2) below the appropriate level. Please check air pressure once a month to ensure environmentally friendly and safe driving.

Adequately managing air pressure is important not only to maximize the features of the tyre but also to avoid an increase in fuel consumption.

Glaph:a loss of fuel consumption is around 2%

Pressure down 50kPa from appropriate level (In case of a 2000cc passenger car)

  • (A) Increase in fuel consumption(%)
  • (B) Driving area
  • Urban zone
  • Suburbs
  • Expressway

Measured in a controlled setting using a 2000cc passenger car Driving speeds (average speed including stoppages): Urban zone 15 km/h, Suburbs 38 km/h, Expressway 78 km/h

Lowers Fuel Economy!
If the tyre pressure is only 155kPa (1.55bar, 22.5psi), 30% lower than the specified pressure of 220kPa (2.2bar, 31.9psi)…

Image:A loss of fuel consumption is around 2%

a loss of fuel consumption is around 2%

Cause of Abnormal Wear!
If the proper inflation pressure is not applied, abnormal wear, as shown below, may occur. In the worst case, the tyre could burst due to under inflation.

Image:Shoulder Wear

Shoulder Wear

If the inflation pressure is too low, it causes excessive wear on both sides of tread.

Image:Center Wear

Center Wear

If the inflation pressure is too high, it causes excessive wear on the center part of tread.

Lack of proper tyre maintenance (e.g. under inflation) causes problems!
About 21% of cars do not have properly maintained tyres.78% of this is due to improper tyre inflation pressure*
*Source: JATMA .

image:Lack of proper tyre maintenance (e.g. underinflation) causes problems!

  • (A) Survey results of improper car maintenance(2007)
  • (B) Improper maintenance of tyres
  • Other 7%
  • Driving over a nail or similar 4%
  • Injury by obstacles 2%
  • Abnormal wear 7%
  • Worn-down tyre grooves 2%
  • Improper tyre inflation pressure 78%
Check your tyre inflation pressure once a month!
How to check the inflation pressure
  • 1. Remove the valve cap on the wheel,attach the inflation pressure gauge to the valve, pressing firmly to avoid escaping air, then check the number.
    Don’t forget to put the valve cap back on when you have finished.
    *Please check the valve base for damage and air leakage.
  • 2. The recommended inflation pressure is written on a label stuck in one of these places inside the driver’s door. You can also refer to the vehicle owner’s manual for the recommended inflation pressure.
  • 3. The inflation pressure should be measured when the tyre is cold. When driving, the temperature inside the tyre rises causing inflation to expand and the inflation pressure to increase. As a result, measurements taken immediately after driving will be inaccurate.
  • 4. Go to a tyre shop when your tyres need to be inflated.

Using a bicycle to illustrate the relation between tyres and air pressure

The more air you put in a bike tyre, the easier it is to peddle and the faster you can go. Conversely, peddling is more difficult when air pressure decreases; you waste energy and get tired quicker. Although the same phenomenon applies to cars as air pressure changes, you feel the link more with a bike as you are expending your own energy.

When air pressure is too low:
  • ・The ride may feel cushy but it is by no means comfortable
  • ・The larger ground contact area results in increased energy loss
When air pressure is too high:
  • ・Energy loss is low, giving a feeling of buoyancy
  • ・It is easier to skid since there is less ground contact area
  • ・The ride is less comfortable since shocks are not absorbed

Image:Using a bicycle to illustrate the relation between tyres and air pressure