Tire pressure is measured in pounds per square inch (PSI). When measuring air pressure in your tires, the tires should be cold, meaning you should check them before driving or at least three hours after driving.
The maximum PSI is not the same for all vehicles. Generally, larger vehicles with larger tires should have 45 PSI, and the tires on smaller cars should have between 30 and 40 PSI.
For the most accurate PSI number, check the side of your tires. There is a number listed on the side of all tires that gives the recommended PSI. Tires should be inflated no more than 5 PSI over the recommended number.
The safest way to drive is with the pressure the same in all your tires. When checking the PSI on your tires, make sure you check all tires and add air as needed to ensure your tires are all equally inflated. Check the air in your cold tires on a weekly or monthly basis to keep the PSI at the recommended level.
