Tires & Wheels
Home › Tires & Wheels › How to Check Tire Pressure
How-To Guide
How to Check Tire Pressure
Checking tire pressure takes about ten minutes a month and improves your fuel economy, your braking distance and how long your tires last. It is the highest-value maintenance job relative to effort on the entire car, and almost nobody does it — usually because they assume the dashboard warning light is doing it for them.
Affiliate disclosure: Car Part Corner is a participant in the Amazon Services LLC Associates Program. We earn from qualifying purchases made through links on this page, at no additional cost to you. This never affects what we recommend or how we tell you to do the job.
It is not. Tire pressure monitoring systems are generally required to warn only at around 25 percent below the recommended pressure, so on a car placarded at 35 PSI the light appears near 26 PSI. By then you have been driving on significantly underinflated tires for weeks. The light is a backstop against a failing tire, not a maintenance tool.
What You Need
- A tire pressure gauge: the one tool this job needs. Forecourt gauges are notoriously inaccurate from heavy use — our tire pressure gauge guide, or check on Amazon
- A way to add air: a portable inflator at home means you can top up cold, which is when the reading is actually correct — our tire inflator guide, or check on Amazon
- Your door jamb placard: free, already on your car, and the only correct source for your target pressure. A mechanical dial gauge is a good backup that never needs a battery — our tire pressure gauge guide, or check on Amazon
Checking Tire Pressure, Step by Step
Find your car's correct pressure — on the door, not the tire
Open the driver's door and look at the sticker in the jamb. It lists the recommended cold pressures, often different front and rear, and sometimes a separate figure for a fully loaded car. Some manufacturers put it in the glovebox or on the fuel filler flap instead.
Do not use the number moulded into the tire sidewall. That is the tire's maximum safe pressure, not your car's recommended one, and inflating to it gives a harsh ride, reduced grip and accelerated wear down the centre of the tread.
Check when the tires are cold
Cold means the car has been sitting for at least three hours, or has been driven less than about a mile. Driving heats the air inside a tire and raises the reading by several PSI, so a warm check will tell you the pressure is fine when it is not.
The practical answer is to check first thing in the morning before going anywhere. If you must check after driving, note that the reading is high and do not let air out to reach the target figure — that leaves you underinflated once things cool.
Take the reading
Unscrew the valve cap and keep it somewhere safe. Press the gauge squarely onto the valve stem in one firm motion — a hiss that continues means you are not seated properly, and air escaping while you read gives you a number that is both wrong and biased low.
Read the value, then do it twice more. A good gauge repeats within a fraction of a PSI; if your readings scatter, the gauge or the seal is the problem rather than the tire.
Adjust to the placard figure
If a tire is low, add air in short bursts and re-check between them — it is much easier to add a little than to let out exactly the right amount. If a tire is over the figure, press the small pin in the centre of the valve briefly to release air.
Set every tire to the placard figure for its position, remembering front and rear may differ. Refit the valve caps: they keep dirt and moisture out of the valve, which is what stops slow leaks developing.
Do not forget the spare
The spare loses pressure sitting in the boot exactly like the others, and it is the one tire nobody checks. Space-saver spares typically run at a much higher pressure than normal tires — often around 60 PSI — so a gauge reading that looks alarming may be correct. Check the sticker on the spare itself.
A flat spare is discovered at the precise moment it cannot be fixed, which is why this step belongs in the routine.
Repeat monthly, and expect seasonal drops
Tires lose roughly 1 PSI a month through normal permeation, with no puncture involved. On top of that, pressure falls about 1 PSI for every 10 degree Fahrenheit drop in ambient temperature — which is why TPMS warnings cluster on the first cold morning of autumn and why so many people think their tire has suddenly developed a leak.
Monthly checks catch both. Before a long trip or a heavily loaded journey, check again and use the loaded figure if your placard lists one.
Safety: If a tire is losing pressure noticeably faster than about 1 PSI a month, it has a puncture or a failing valve and needs inspecting rather than repeated topping up. Driving on a significantly underinflated tire builds heat in the sidewall and can cause it to fail at speed.
Common Mistakes
Using the number on the tire sidewall
That figure is the tire's maximum pressure, not your car's recommendation. Inflating to it produces a harsh ride, less grip and rapid wear down the middle of the tread. The correct number is on the door jamb placard and is specific to your vehicle.
Checking after driving
Warm tires read several PSI high. If you set them to the placard figure while warm, they will be underinflated once cool — which is the opposite of what you were trying to achieve. Check cold, or account for the difference and do not bleed air out.
Trusting the TPMS light
Most systems are only required to warn at around 25 percent below the recommended pressure. Fuel economy, braking and tread wear have all been suffering long before it illuminates. Treat it as an alert for a failing tire, not as a monthly reminder.
Skipping the spare
It loses pressure like every other tire, and it is the only one whose condition you find out about at the worst possible moment. Check it whenever you check the others.
Ten minutes a month, cold, using the door jamb figure. It is the cheapest thing you can do for fuel economy, braking distance and tire life, and it costs nothing beyond owning a gauge worth trusting.
Frequently Asked Questions
What should my tire pressure be?
Use the figure on the sticker inside the driver's door jamb, which is specific to your vehicle and often differs front to rear. Do not use the number on the tire sidewall — that is the tire's maximum safe pressure, not your car's recommended one, and inflating to it degrades ride, grip and tread life.
How often should I check tire pressure?
Monthly, and before any long or heavily loaded trip. Tires lose around 1 PSI a month through normal permeation regardless of punctures, and pressure also drops roughly 1 PSI for every 10 degree Fahrenheit fall in temperature. Both add up faster than most people expect.
Should I check tire pressure hot or cold?
Cold — meaning the car has sat at least three hours or been driven less than about a mile. Driving heats the air and raises the reading by several PSI. If you check warm, do not release air to hit the target figure, or the tires will be underinflated once they cool.
Why does my tire pressure light come on when it gets cold?
Air contracts as it cools, so pressure falls about 1 PSI for every 10 degree Fahrenheit drop. A tire set correctly on a warm day can be several PSI low on the first cold morning of the season, which is enough to trigger the warning. It is normal physics rather than a leak — but do top the tires back up.
Is it bad to overinflate tires?
Yes. Overinflation reduces the contact patch, which lengthens braking distances and reduces grip, produces a harsher ride, and wears the centre of the tread far faster than the shoulders. It is not a safe way to improve fuel economy. Use the placard figure.
Related Guides
How We Write Guides
Every product named in the “what you need” section is one we have researched and written about separately, and each links to that guide so you can see the reasoning rather than taking a recommendation on trust. We publish no prices, because they change faster than we can update pages. Where a job carries genuine risk we say so plainly rather than burying it, and where a job is beyond a home mechanic we say that too. Last reviewed August 10, 2026.
A note on safety: A tire losing more than about 1 PSI a month has a fault rather than normal permeation. Have it inspected instead of topping it up repeatedly — an underinflated tire builds heat and can fail at speed.