The recommended air pressure for tires on a car depends on the size of the vehicle. The pressure normally ranges between 28 and 36 psi. The air pressure for tires of larger commercial trucks can easily exceed more than 100 psi.
The exact tire air pressure recommended by the auto manufacturer is found in at least one of three places. The first and most common is a sticker inside the door jam. The sticker lists what type of tires fit the vehicle, as well as the recommended pressure for the tires. If the sticker is not present, check the glove compartment. The same sticker should be there with the correct specifications. If all else fails, check the car's service manual, which lists all the basic maintenance information for the car.