Correct tire inflation is critical for fuel economy, tread wear, and handling. A tire pressure gauge measures the air pressure in pounds per square inch (PSI) or kilopascals (kPa). It works by pushing against the tire valve stem core, allowing air to press against a calibrated piston, dial, or digital sensor. For the most accurate reading, check your tire pressure in the morning when the tires are cold. Tires heat up as you drive, which raises the internal pressure and gives a false reading.
Mechanic Glossary
Tire Pressure Gauge
A diagnostic tool used to measure the air pressure inside a vehicle's tires.
Frequently Asked Questions
Look at the placard on the driver's door jamb. Do not use the maximum pressure listed on the tire sidewall, as that is the limit for the tire, not the vehicle's specification.
Dial and digital gauges are generally more accurate and easier to read than pencil-style slide gauges, which can stick or wear out over time.
You should check your tire pressure at least once a month and before any long road trip, as tires naturally lose about 1 PSI of pressure per month.