How do I check and maintain the correct tire pressure?

Measure tire pressure with a gauge when tires are cold (not driven for 3+ hours) and inflate to the PSI listed on the driver's door-jamb sticker -- never the maximum printed on the tire sidewall.

Most cars from 2008 onward have a Tire Pressure Monitoring System that lights a dashboard icon (a tire cross-section with an exclamation mark) when any tire drops significantly below the recommended PSI. Treat the warning as a prompt to check all four tires with a gauge and inflate to spec.

Tire pressure rises and falls roughly 1 PSI for every 10 degrees F change in ambient temperature. A tire inflated to 35 PSI in summer can drop to 29 PSI by mid-winter, so check and adjust pressure at each major seasonal shift and whenever temperatures swing more than 20 degrees F over a few days.