Check Your Tire Pressure Day: March 11

March 11th marks “Check Your Tire Pressure Day.” Monitoring the air pressure inside your tires is, without a doubt, a good habit to get into, as it ensures a safe ride for your passengers and helps you get better fuel efficiency.

The U.S. Department of Transportation estimates that Americans waste as much as 5 million gallons of gas per day by driving cars with under-inflated tires. On top of that, driving on tires with low pressure also wears them down faster, so you might burn through your set a year sooner than you should. Under-inflated tires are a big safety risk, too—they can cause instability, unsafe braking and cornering, and even tire failure.

Thankfully, checking your tire pressure is easy. Most modern cars have a tire pressure light that comes on when your pressure is dangerously low, but it’s a good idea to keep a close eye on your tire pressure even when the indicator isn’t illuminated.

Digital tire gauges only cost about $10, and they’re much more accurate than the traditional, pencil-style gauges, so it might be a good idea to spring for one and keep it in your glove compartment. In a pinch, you can check your pressure using a gas station air pump, which will usually have a gauge on the hose (although these can sometimes be hard to read).

Most people refill their tires at gas stations, which usually only costs a few quarters. Alternatively, you can buy a portable air compressor that allows you to refill your tires at home.

To determine the correct PSI for your car’s tires, open the driver’s side door and look at the yellow sticker on the doorjamb, or consult your owner’s manual. Do not fill your tires according to the number on the tires themselves. The number on the sidewall of your tire is the maximum PSI, indicating the PSI for which the tire will support the maximum carry load.

Once you find out the recommended PSI, remove the valve caps from all four tires. (Make sure to put the caps in a safe place, like your pocket—they’re easy to lose!) Press your tire gauge to the valve stem, letting a little air out to get a reading. If the pressure is too low, attach the hose fitting of the air compressor to the valve stem and press down on the lever to allow the flow of air. Once all four of your tires are inflated to the recommended PSI and your valve caps are replaced, you’ll be good to go!