Check your tire pressure once a month, and again before long trips

The standard recommendation is to check your tire pressure at least once a month. Most tire shops and vehicle manufacturers suggest this monthly check as the baseline to catch slow leaks and normal pressure loss before they become a safety problem. You should also check pressure before any trip longer than a few hours, since underinflated tires wear faster and can overheat on highway driving.

Tire pressure naturally drops about 1 pound per square inch (PSI) every month, even on tires with no leak. Cold weather accelerates this loss — pressure can drop 1 PSI for every 10-degree drop in outside temperature. If you live somewhere with seasonal temperature swings, you may need to check more often in fall and winter.

The correct pressure for your vehicle is printed on a sticker inside the driver's door jamb, not on the tire sidewall itself. The sidewall shows the maximum pressure the tire can hold, which is different. Check the door jamb sticker to know what number you are aiming for.

Key Takeaways

  • Check tire pressure once a month as a routine, using the PSI number on your driver's door jamb sticker, not the number on the tire itself.
  • Temperature changes cause pressure to drop faster — expect to check more often in cold months or when seasons shift.
  • Check pressure before long highway trips, since underinflated tires overheat and wear unevenly at higher speeds.
  • Check all four tires plus the spare if your vehicle has one, since a slow leak can develop in any tire without warning.
  • Pressure readings are most accurate when tires are cold — at least three hours after driving or before the car has been in direct sun.

When temperature changes require extra checks

If you live in a climate with cold winters, plan to check tire pressure when the season shifts. A 30-degree temperature drop can lower tire pressure by 3 PSI or more, which is enough to trigger a low-pressure warning light on newer vehicles. This does not mean your tire has a leak — it is straightforward physics.

Check tires in early fall before temperatures drop, and again in early spring when they rise. If you drive between climates frequently — for example, driving from a warm city to mountains — check before you leave and after you arrive, since the pressure will change during the drive.

How to check tire pressure correctly

You need a tire pressure gauge, which costs $5 to $15 at any auto parts store or gas station. Digital gauges are easier to read than dial gauges, but both work. Many gas stations have free air pumps with built-in gauges, though the gauges on these pumps are often less accurate than a handheld gauge.

Check pressure when tires are cold — meaning at least three hours after you last drove, or before the car has been in direct sun for more than an hour. Driving heats tires and raises pressure temporarily, giving you a false high reading. If you must check after driving, wait at least three hours.

Remove the valve cap from the tire, press the gauge onto the valve stem firmly until you hear a small hiss, and read the number. Write down the pressure for each tire. Then check the door jamb sticker to see if any tire is below the recommended PSI. If a tire is low, drive to a gas station or tire shop and add air until it matches the target.

What to do if one tire keeps losing pressure

If one tire consistently reads lower than the others, or drops noticeably between your monthly checks, it has a slow leak. A slow leak can come from a puncture you did not notice, a damaged valve stem, or a bead leak where the tire meets the rim.

Do not ignore a slow leak. A tire that loses pressure gradually will eventually become dangerously underinflated, and you may not notice until the warning light comes on — by which point the tire has already been running low for days. Take the vehicle to a tire shop and have them inspect that tire. Many slow leaks can be repaired for $10 to $20 if caught early.

Checking the spare tire

Check your spare tire pressure at the same time you check the four main tires. A spare that has been sitting unused for years can lose pressure slowly, and you do not want to discover it is flat when you actually need it. The correct pressure for a spare is usually printed on the spare itself or in your owner's manual, and it is often higher than the pressure for regular tires.

If your vehicle has a full-size spare, treat it like a regular tire and check it monthly. If you have a compact or temporary spare, check it every three months since these are used less often and pressure loss is less noticeable.

Signs that pressure is too low between checks

Do not wait for your monthly check if you notice any of these signs: a low-pressure warning light on your dashboard, a tire that looks visibly flatter than the others, vibration or pulling to one side while driving, or a bulge on the tire sidewall. Any of these means at least one tire is significantly underinflated and needs attention before you drive far.

Pull over safely, turn on hazard lights, and check the pressure with your gauge if you have one. If a tire is more than 5 PSI below the target, drive slowly to the nearest gas station or tire shop to add air. If you cannot reach a station safely, call for roadside information rather than driving on a severely underinflated tire.

Frequently Asked Questions

Should I check tire pressure when tires are hot or cold?

Always check when tires are cold — at least three hours after driving or before the car has been in sun. Driving heats the air inside the tire and raises pressure by 2 to 4 PSI temporarily. A reading taken on hot tires will be higher than the actual resting pressure and may cause you to underinflate.

What is the difference between the pressure on the tire and the pressure on my door jamb?

The number on the tire sidewall is the maximum pressure that tire can safely hold. The number on your door jamb is the correct pressure for your vehicle's weight and handling. Always use the door jamb number. Inflating to the sidewall number will overinflate your tires and cause uneven wear.

Do I need to check tire pressure if my car has a tire pressure monitoring system?

The monitoring system alerts you when pressure drops significantly, but it does not replace monthly checks. The light usually comes on only when pressure is already 25% below target, meaning your tires have been running low for a while. Monthly checks catch slow leaks much earlier.

Can I check tire pressure at a gas station for free?

Most gas stations have free air pumps, and many have gauges built into the pump. However, these gauges are often less accurate than a handheld gauge you own. If you use a station gauge, check the reading twice to make sure it is consistent, and consider buying a $10 digital gauge for more reliable readings at home.