Check tire pressure with a gauge when tires are cold, before driving or at least three hours after driving
Tire pressure is measured in pounds per square inch, or PSI. The correct pressure for your vehicle is printed on a sticker inside the driver's door jamb, not on the tire itself. The number on the tire is the maximum pressure the tire can safely hold, which is different. You need a tire pressure gauge — a small handheld tool that costs between $5 and $20 — and about two minutes per tire.
Cold tires give you an accurate reading. Driving heats the air inside the tire and raises the pressure by 1 to 3 PSI. Check pressure before you drive in the morning, or wait at least three hours after driving if you check later in the day. If you check warm tires and they read high, that does not mean they are overinflated — it means the reading is unreliable.
Key Takeaways
- Find the correct PSI on the driver's door jamb sticker, not on the tire sidewall, and check pressure when tires are cold for an accurate reading.
- A basic tire pressure gauge costs $5 to $20 and takes two minutes to use per tire; digital gauges are more precise than stick gauges but both work.
- Remove the valve cap, press the gauge onto the valve stem firmly until you hear air stop hissing, and read the number that appears on the gauge display or dial.
- If pressure is low, add air at a gas station pump or tire shop; if it is high, press the valve stem with a small tool to release air slowly.
- Check tire pressure once a month and before long trips, because tires naturally lose 1 to 2 PSI per month even without a leak.
Where to find the correct PSI for your vehicle
Open the driver's side door and look at the door jamb — the vertical edge where the door closes. You will see a sticker or label with vehicle information. This sticker lists the correct tire pressure in PSI for your specific car, truck, or SUV. It may also list different pressures for front and rear tires, or different pressures depending on how heavily loaded the vehicle is.
Do not use the number printed on the tire sidewall. That number is the maximum pressure the tire can hold, not the pressure your vehicle needs. Using the sidewall number will overinflate your tires and cause uneven wear, poor handling, and a harsher ride.
Types of tire pressure gauges and how they work
Stick gauges are the cheapest option, usually $5 to $10. They have a small rod that pops out when you press the gauge onto the valve stem. You read the pressure from numbers printed along the rod. They are durable and need no batteries, but the reading can be hard to see and less precise than other types.
Digital gauges cost $15 to $30 and display the pressure on a small LCD screen. They are easier to read and more accurate than stick gauges. Some have a backlight for checking tires in dim light. They run on a battery that lasts several years.
Dial gauges have a round face with a needle, similar to an old clock. They cost $10 to $20 and are accurate and straightforward to read, but the needle can stick if the gauge is dropped or stored poorly. Gas station air pumps often have a built-in dial gauge, so you can check pressure while you add air.
Step-by-step process for checking each tire
Start with the vehicle parked and the engine off. Remove the plastic valve cap from the first tire by twisting it counterclockwise. Set the cap somewhere you will not lose it — a cup holder or your pocket works.
Press the gauge onto the valve stem firmly and straight on. You may hear a brief hiss of air escaping. Hold the gauge in place for one to two seconds until the hissing stops. The pressure reading will appear on the gauge — either on the rod, the screen, or the dial, depending on the type you are using.
Write down the reading or remember it. Remove the gauge and replace the valve cap by twisting it clockwise until snug. Do not over-tighten — hand-tight is enough. Repeat this process for all four tires, and the spare if your vehicle has one.
What to do if pressure is too low or too high
If one or more tires read lower than the door jamb sticker says they should, add air at a gas station pump or tire shop. Most gas stations have free air pumps near the fuel pumps. Attach the pump hose to the valve stem, press the lever, and watch the gauge on the pump. Stop when the pressure reaches the target number. Check the pressure again with your own gauge to confirm.
If pressure is higher than the target, you need to release air. Use a small tool — a pen cap, a key, or the small tool built into some gauges — and press it against the center of the valve stem for one second at a time. Check the pressure after each release. Releasing air is slower than adding it, so go slowly to avoid dropping the pressure too far.
If a tire is significantly low — more than 5 PSI below the target — and you have not driven on a flat tire recently, you may have a slow leak. A tire shop can find and repair the leak, or patch or replace the tire if it is damaged.
How often to check tire pressure and when it matters most
Check tire pressure once a month as part of routine vehicle maintenance. Tires naturally lose 1 to 2 PSI per month as air molecules pass through the rubber, even if there is no leak. Seasonal temperature changes also affect pressure — cold weather can lower pressure by 1 PSI for every 10 degrees Fahrenheit the temperature drops.
Check pressure before long road trips, especially if you will be driving at highway speeds for several hours or carrying extra weight. Underinflated tires generate more heat, which can lead to blowouts on long drives. Check pressure again after the trip if you drove more than 500 miles.
Check pressure after hitting a pothole, curb, or other road hazard that could have damaged a tire or bent a wheel. A sudden drop in pressure after impact suggests a puncture or leak that needs when ready attention.
Common mistakes that lead to inaccurate readings
Checking warm tires is the most common mistake. Pressure rises as tires heat up from driving, so a warm tire will read 2 to 3 PSI higher than it actually is when cold. This leads you to think the tire is properly inflated when it is actually underinflated. Always check in the morning or wait several hours after driving.
Pressing the gauge on at an angle instead of straight on can cause an incomplete seal and an air leak, giving you a false low reading. Press the gauge firmly and straight onto the valve stem until the hissing stops.
Forgetting to replace the valve cap leaves the valve stem exposed to dirt and moisture, which can damage the valve and cause a slow leak over time. Replace the cap every time, even if you are checking pressure again in a few days.
Frequently Asked Questions
Can I check tire pressure at a gas station without my own gauge?
Yes. Most gas station air pumps have a built-in gauge on the pump itself. Press the pump nozzle onto the valve stem and read the gauge on the pump. The reading is usually accurate, though older pumps can be less reliable. If the pump gauge and your personal gauge disagree, trust your personal gauge.
What if I cannot find the valve stem?
The valve stem is a small rubber or metal tube sticking out from the wheel rim. On most vehicles, it is on the outer edge of the rim facing outward. If you cannot see it, the wheel may be positioned so the stem is on the back side of the rim. Rotate the wheel slightly or look from a different angle. The valve cap is usually the same color as the stem, so look for the cap first.
Does tire pressure change with the seasons?
Yes. Cold weather lowers tire pressure and warm weather raises it. For every 10-degree Fahrenheit drop in temperature, tire pressure drops about 1 PSI. In winter, check pressure more often because cold air will lower it below the target. In summer, check pressure in the morning before the sun heats the tires.
What does it mean if one tire keeps losing pressure?
A tire that loses pressure faster than others likely has a slow leak. The leak could be a puncture from a nail or thorn, a damaged valve stem, or a crack in the sidewall. A tire shop can locate the leak by submerging the tire in water and looking for bubbles, then repair it with a patch or plug if the damage is small enough.
Can I drive on a tire that is 5 PSI below the recommended pressure?
You can drive short distances, but you should not make it a habit. Underinflated tires wear faster, reduce fuel economy, and generate more heat. On highway speeds or long drives, underinflation increases the risk of a blowout. Add air as soon as you can reach a gas station or tire shop.