Automobile maintenance, including checking and adjusting tire pressure is often easy to perform. And yet, many people do not own a portable air compressor and many models are modestly priced. The benefit of owning one is being able to inflate the tires of any vehicle in the comfort of your own driveway or garage. Drastic ambient temperature changes cause tires to fluctuate in air pressure. Under- and over-inflated tires are one of the leading causes in premature tread wear.
Locate the tire placard for the vehicle (usually in the driver's side door jamb) or the owner's manual to learn the recommended tire pressure for the front and rear tires (it's not uncommon on some vehicles to have a lesser air pressure recommended for the front tires than the rear, but not always the case) for the vehicle. The tire placard should be the tire pressure adhered to, rather than the maximum tire pressure stamped on the sidewall of the respective tires.
Plug the portable air compressor into an electrical outlet or the power source of the vehicle. If using the vehicle's power source, it may be necessary to turn the ignition key to the accessory power position to provide portable power to the compressor.
Remove the tire valve caps on all four tires. Place the caps in a pocket to prevent losing them.
Position the air compressor near the tire and tire valve stem, but use the tire gauge to test the air pressure in the tire before attaching the air chuck of the compressor to the tire valve. Press the chuck of the gauge onto the valve stem as evenly as possible to check the air pressure. The gauge will produce a small stick that will protrude out of the gauge (or a digital reading if using a digital gauge) to display the air pressure inside the tire in pounds per square inch (PSIs).
Place the air chuck of the air compressor onto the tire valve stem (if adding air is necessary). To release air in over-inflated tires, place the chuck up to the valve and press inward until air is released from the valve core of the stem. Some air chucks on certain compressors feature a locking device to clamp the chuck onto the valve stem while others may require holding the air chuck (much like the tire gauge) onto the stem while inflating the tire.
Turn on the power switch to the air compressor, but only allow the compressor to run for about 30 seconds (depending on how low the tire is) until figuring out how quickly and how powerful the compressor is. Some compressors can fill car tires within a minute and a half, while others may take more than five minutes.
Adjust the tire pressure by continuing to run the compressor (if necessary) or using the air chuck of the compressor to release air from the valve stem (if necessary) until the recommended tire pressure listed on the tire placard (or owner's manual of the vehicle) has been reached. Retest the pressure with the gauge in 30-second to one-minute intervals (depending on how low the tire is) with the tire pressure gauge.
Replace the valve stem cap and then move to the next tire until all four tires on the vehicle have been adjusted to the recommended tire pressure listed on the tire placard (or owner's manual).
