You can save money on gas—and make your car ride smoother—by maintaining proper air pressure in your tires. Here's exactly what you need to know to check your tires' air pressure.
• Air pressure gauge (gas stations have air hose gauges, but they're usually not as accurate)
• Air compressor (your own or one at a gas station)
1. First, find your car manufacturer's specifications for the proper tire pressure for your car. You probably can find them in your manual, on a sticker on the driver's side door jamb, or inside the glove compartment.
2. Park your car by the air dispenser at the gas station. (Have some quarters handy—it's likely to cost a few dollars.) Be sure your tires are cool: Warm air inside the tires can cause them to expand and might result in an inaccurate reading.
3. Remove the cap from the valve on the tire and place it somewhere safe.
4. Push the air pressure gauge firmly over the valve until you get a reading. If the tire needs air, first check for obvious wear and tear (filling tires that are worn or punctured can be dangerous). If the tire is in good shape, push the compressor's nozzle onto the valve to add air in short bursts, until you no longer hear air being released. Some compressors allow you to preset the pressure; otherwise, check the pressure with your gauge after each burst of air. Never overinflate your tires; it can increase your risk of a blowout. If you accidentally add too much air, let some of it out by depressing the valve.
5. When you're done, replace the valve cover, tightening it until it's snug.