It's important to have the proper air pressure in your tires, as underinflation may lead to tire failure. The right amount of air for your tires is specified by the vehicle manufacturer and is shown on the vehicle door edge, door post, glove box door or fuel door. It is also listed in the owner's manual.

1. When you check the air pressure, make sure the tires are cool - meaning they are not hot from driving even a mile. (NOTE: If you have to drive a distance to get air, check and record the tire pressure first and add the appropriate air pressure when you get to the pump. It is normal for tires to heat up and the air pressure inside to go up as you drive. Never "bleed" or reduce air pressure when tires are hot.)
2. Remove the cap from the valve on one tire.
3. Firmly press a tire gauge onto the valve.
4. Add air to achieve recommended air pressure.
5. If you overfill the tire, release air by pushing on the metal stem in the center of the valve with a fingernail or the tip of a pen. Then re-check the pressure with your tire gauge.
6. Replace the valve cap.
7. Repeat with each tire, including the spare. (NOTE: Some spare tires require higher inflation pressure.)
8. Visually inspect the tires to make sure there are no nails or other objects embedded that could poke a hole in the tire and cause an air leak.
9. Check the sidewalls to make sure there are no gouges, cuts, bulges or other irregularities. NOTE: Air pressure in a tire goes up (in warm weather) or down (in cold weather) 1-2 pounds for every 10 degrees of temperature change.
   

INFLATION PRESSURE

Proper tire inflation pressure is shown on the vehicle's tire placard. If there is no tire placard, consult the vehicle owner manual or check with the tire or vehicle manufacturer for the proper tire inflation pressure.
Proper tire inflation pressure is another important requirement for the tire to obtain its peak tread life, safety and performance characteristics. Proper tire inflation pressure ensures correct sidewall deflection and operating temperature. Underinflation causes excessive heat, lowers load carrying capacity, and can result in irregular wear and presents safety hazards. Underinflation increases energy loss, therefore, fuel consumption and tire life become poorer.

One of the most common causes of HPT damage is Underinflation (runflat)-continued driving on a radial with no or minimal inflation pressure. It may be difficult to realise that an HPT has improper inflation pressure, which is why it is essential to actually check the pressure with an accurate tire gauge frequently and before long trips.

Yokohama recommends checking the inflation pressure every two weeks for HPTs when tires are cool (driven less than a kilometre or so). Never reduce inflation pressure when tires are hot from driving.

Inflation pressure increases when the tires are hot so the hot inflation pressure reading will normally be higher, as much as 28 kPa. tire inflation pressure will vary with ambient temperature. A drop of 10 C causes a corresponding drop of approximately 14 kPa. Sustained high speed driving conditions may call for higher inflation pressure, For example, European standards recommend an increase of 30kPa (0.3bar), and special cases for higher increases may be recommended by the auto makers. Be sure to consult the vehicle owner manual if sustained high speed driving is expected. When a passenger car is towing a trailer the inflation pressure of the rear tires should be adjusted for the load of the towing hook. tire valves should be capped to keep dirt and moisture out. They should be replace whenever the tire is changed.