There’s a lot riding on your tires– quite literally; they are the only part of your vehicle that should be in contact with the road. That means good tire condition and care is critical. There’re a few things you can do to maximize tire life, not the least of which is maintaining the correct tire pressure. Running too high or too low of pressures can adversely affect rate of tread wear, fuel economy of the vehicle, as well as vehicle ride quality. If you have never had to check your tire pressure yourself, here’s a quick rundown of how to do it.

Get a quality tire pressure gauge

A good quality tire pressure gauge can be obtained at any automotive parts store, usually for under $10.

Determine the proper tire pressure for your vehicle

Correct tire pressure varies between vehicles. The easiest way to determine the correct pressure for your vehicle is the tire pressure specification sticker, which is usually located in one of two places; On the driver door jamb, which is the part the door closes into, or on the inside of the fuel door. This sticker contains a plethora of numbers specifying the pressure in both psi (pounds per square inch) and bar (barometric pressure) for the front and the rear tires at partial load, as well as separate pressures for fully loaded vehicles. The pressure listed are also “cold” pressures, meaning that these pressures are specified on cold tires. If you are inflating tires that have been warmed up by driving, you may need to compensate these pressures, which will be covered later.

Check your current tire pressure

First you should check the pressure in each tire to determine if you need to add some. Even if you have a newer car with an onboard tire pressure monitoring system, it's still a good idea to occasionally check the pressure manually. Make sure the vehicle is parked securely. Remove the valve stem cap and set it aside for now. Take the tire pressure gauge, and firmly press the fitting straight onto the tire valve. The tire pressure gauge should now indicate the current pressure of the tires. It’s best to check the tire pressure cold, before the car is driven anywhere. If you check it after the vehicle has been driven, you will need to compensate by subtracting about 3-5 psi from the current indicated pressure. This will give you what your current “cold” pressure would be, so you can compare to the pressures listed on the sticker. Don’t forget to put your valve stem cap back on. If you’re pressures are ok, then you can stop here. If they’re low, continue on.

Locate a source of compressed air

Most fuel stations have an air compressor you can use to fill your tires. Depending on your state, they may or may not charge for use of it, though it’s generally quite cheap if they do. In California for example, service stations provide air for free because having low tire pressure causes lowered fuel economy which puts more pollutants into the air.

Add air to the tires

Adding air is a simple process. Once again you will remove the valve stem cap and set it aside. The air hose (chuck) will have a tip similar to that of the tire pressure gauge. Simply push the fitting of the air chuck onto the tire valve, and air will automatically flow in. Some chucks have a button or lever that needs to be depressed to allow air to flow. Add air for about 5 seconds at a time, and check the pressure using your gauge after each 5 seconds until you obtain the desired pressure. If you overfill the tires and need to remove some air, the back side of the gauge has a small pin that you push into the center of the valve to release air. Do this slowly, as the pressure releases quickly. If your car is equipped with a spare tire, whether compact or full size, make sure to check it's pressure and add if necessary. Don’t forget that you may need to compensate the pressure as noted above if the tires have been warmed up by driving for more than 15 minutes. Reinstall your valve stem cap and now you’re done.

It’s totally normal for tires to lose a bit of pressure over a long period of time. If you find yourself needing to add air more frequently, such as weekly or even monthly, you should have your tires inspected for leaks or damage by a qualified professional, such as one available from YourMechanic. Also, while you’re checking the tire pressure, be sure to check the overall condition of your tires to ensure that you’re always driving on good condition tires.

This article originally appeared on as How To Add Air To Your Tires and was authored by Toby Schultz.

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