What you need before you start

You will need an air pump, a tire pressure gauge, and the correct pressure number for your vehicle. The pump can be electric (plugs into a wall outlet or your car's 12-volt outlet) or manual (hand-operated). Most gas stations have free electric pumps available to customers. The tire pressure gauge is a small handheld tool that costs $5 to $15 and reads the air pressure inside each tire.

Find your vehicle's correct tire pressure by opening the driver's side door and looking at the sticker on the inside edge of the door frame. This sticker lists the pressure in PSI (pounds per square inch) for your front and rear tires — they may differ. Do not use the pressure number printed on the tire itself; that is the maximum pressure the tire can hold, not the pressure your vehicle needs.

Key Takeaways

  • Your vehicle's correct tire pressure is on a sticker inside the driver's door frame, not on the tire itself.
  • Check your tire pressure with a gauge before adding air, because overinflated tires wear faster and reduce fuel economy.
  • Most gas stations offer free air pumps; electric pumps are faster and easier than manual pumps.
  • Add air in short bursts and check pressure after each burst to avoid overshooting the target pressure.
  • Check all four tires, including the spare if your vehicle has a manual spare tire.

Check your current tire pressure first

Before you add any air, measure what is already in each tire. Unscrew the valve cap on the first tire — it is a small plastic or metal cap on the tire stem. Press the tire gauge firmly onto the valve stem until you hear a small hiss of air. The gauge will display a number in PSI. Write down the pressure for each tire.

Check all four tires, and the spare if you have a manual spare tire mounted on the outside of your vehicle. Tire pressure changes with temperature, so a tire that was properly inflated yesterday may read lower on a cold morning. If any tire is more than 3 PSI below the target pressure on your door sticker, it needs air.

Locate an air pump and position your vehicle

Gas stations, tire shops, and some car washes have air pumps available to the public. Most are free. Drive to the pump and position your vehicle so the tire you are filling is closest to the pump. You may need to pull forward, backward, or turn the wheel to reach the valve stem easily. Leave the engine running if the pump is electric and powered by your vehicle's 12-volt outlet; turn it off if the pump plugs into a wall outlet.

If you are using a manual pump at home, place it on a flat surface near the tire you are filling. Manual pumps are slower than electric pumps — expect to spend one to two minutes per tire — but they work anywhere without power.

Add air in short bursts and recheck pressure

Remove the valve cap and set it where you will not lose it. Attach the pump nozzle firmly to the valve stem. If you are using an electric pump, press the button or trigger to start air flowing. If you are using a manual pump, push and pull the handle. Add air for three to five seconds, then stop and detach the pump.

when ready check the pressure with your gauge. If the pressure is still below the target, add another short burst and check again. Repeat this cycle until the pressure matches the target number on your door sticker. It is easier to add a small amount of air than to remove air if you overshoot, so err on the side of caution with each burst.

Once the pressure is correct, reattach the valve cap firmly. Move to the next tire and repeat the process for all four tires. If your vehicle has a manual spare tire mounted on the outside, check and fill that as well — a flat spare is useless in an emergency.

What to do if you overfill a tire

If you add too much air and the pressure is now higher than the target, you can release some air by pressing the small pin inside the valve stem with your finger or a small tool. Press gently and briefly, then check the pressure again. This takes practice; most people find it easier to drive to a tire shop and ask staff to bleed off the excess air.

Overinflated tires wear faster in the center of the tread and reduce your vehicle's fuel economy. They also ride harsher and are more prone to punctures. If you are more than 5 PSI over the target pressure, it is worth the time to correct it.

How often to check and refill

Check your tire pressure once a month and before long trips. Tires naturally lose air over time — expect to lose 1 to 2 PSI per month in normal conditions. Cold weather accelerates this loss; a tire may drop 1 PSI for every 10-degree drop in outside temperature. If you notice a tire losing pressure faster than normal, it may have a slow leak and should be inspected by a tire shop.

Many newer vehicles have a tire pressure monitoring system (TPMS) that alerts you on the dashboard when a tire is significantly underinflated. This warning means at least one tire is 25% below the target pressure. Do not ignore this warning — drive to an air pump or tire shop and refill when ready.

Frequently Asked Questions

Can I use the pressure number printed on the tire sidewall?

No. That number is the maximum pressure the tire can safely hold, not the pressure your vehicle needs. Using it will overinflate your tires and cause them to wear faster and ride harshly. Always use the pressure number on the sticker inside your driver's door frame.

What if I cannot find the valve stem?

The valve stem is a small rubber or metal tube sticking out from the tire rim. On most vehicles, it faces outward and is straightforward to spot once you know what to look for. If the stem is hidden behind the wheel, you may need to turn the steering wheel or rotate the tire slightly to access it. If you still cannot find it, ask a gas station attendant to point it out.

Do I need to check tire pressure when the tires are cold or hot?

Check pressure when the tires are cold — before you have driven the vehicle or at least three hours after driving. Driving heats the tires and increases air pressure temporarily, giving you a false reading. If you must check after driving, add 4 PSI to the target pressure to account for heat, then recheck when the tires cool down.

What happens if I drive on underinflated tires?

Underinflated tires wear faster on the outer edges, reduce fuel economy, and generate excess heat that can lead to blowouts. They also make your vehicle harder to steer and increase stopping distance. Driving on significantly underinflated tires is unsafe and can damage the tire permanently.

Can I add air to a tire while it is still hot from driving?

You can, but the reading will be inaccurate because heat increases air pressure temporarily. If you must add air to a hot tire, add less than you think you need, then recheck the pressure after the tire cools. You can always add more air later, but removing air is inconvenient.