Measuring a car's tire pressure involves pressing a tire air pressure gauge onto the tire valve stem and reading the meter or viewing the digital number, according to DMV.org. The reading is measured against the car manufacturer's recommendations for tire air pressure, which are found in the owner's manual.
Take the reading when the tires are cold, usually in the morning, because a reading is inaccurate if it is taken when the tires are hot from use, claims Edmunds.com. A reading that is 3 psi below the car manufacturer's recommendation results in a 1 percent increase of fuel use, even though this difference does not seriously affect driving safety. Tire air pressure should be manually checked regularly, even if the car comes with an electronic system that monitors tire air pressure, states DMV.org. Air pressure gauges provide quick and accurate readings that can alert the driver to any potential problems before they become worse. Tires should be within 5 psi of the car manufacturer's air pressure recommendation.
Experts recommend avoiding overinflation and underinflation of tires, since either of these conditions can result in uneven wearing of the tread and increased risk of damage from road debris, explains Pep Boys. Check tire air pressure whenever the seasons change and before using the car.