A decrease of even one psi of tire air pressure can result in drop of 0.4% in fuel economy and therefore, it makes sense to check it regularly every month or at least before a long trip. This is especially true because your 4 tires carry different loads, which can affect its air pressure. That is why; tire air pressure must be monitored regularly for each individual tire. Remember: it is the air pressure that carries the load not the tire.

Tire inflation pressure must be checked when the tire is cold like in the morning before starting your vehicle. In winter times, a drop in tire pressure is more common and thus requires more frequent check ups. Do not depend on gas stations for using a tire pressure gage, which is normally out of calibration. Get your own tire gage and keep it in your glove box where you get it when you need it. A small investment like this will surely protect you in the long run.