Vehicle tires should be checked and inflated to the manufacturer's recommendations at least once a month. The information is normally available on a sticker in the doorjamb on the driver side. It is also found in the owner's manual.
Tire pressure may vary for the front tires versus the back tires. Consult the owner's manual. Check pressure when the tires are cold. Checking first thing in the morning provides an accurate reading. Tires heat up, so do not measure pressure after driving. They cool down in about a half hour. Keep tires properly inflated to improve fuel economy, reduce tire wear, and facilitate safe driving.