Check your tyre pressure with a gauge when the tyres are cold, ideally before you drive or at least three hours after you stop

Tyre pressure is measured in pounds per square inch (PSI) or bar, depending on your vehicle and where you live. The correct pressure for your car is not printed on the tyre itself — it is printed on a sticker inside the driver's door jamb, on the fuel door, or in your owner's manual. Check that number first, because it is specific to your vehicle's weight and suspension.

You will need a tyre pressure gauge, which costs between £5 and £20 and is available at any petrol station, supermarket, or online. Digital gauges are easier to read than dial gauges, but both work. Many petrol stations also have air pumps with built-in gauges, so you can check and inflate in one stop.

The reason you check when tyres are cold is that driving heats the rubber and raises the pressure inside by 4 to 6 PSI. If you check after driving, you will get a false high reading and may under-inflate, which wastes fuel and wears the tyre unevenly. "Cold" means the car has been parked for at least three hours or you have driven less than a mile at low speed.

Key Takeaways

  • Your vehicle's correct tyre pressure is printed on a sticker inside the driver's door jamb or fuel door, not on the tyre wall itself.
  • Check pressure when tyres are cold — before you drive or at least three hours after you stop — because driving heats the air inside and raises the reading.
  • A tyre pressure gauge costs £5 to £20 and is the only tool you need; many petrol stations have free gauges built into their air pumps.
  • Pressure that is too low wastes fuel and causes uneven wear; pressure that is too high makes the tyre ride hard and can damage the sidewall.

Where to find your vehicle's correct pressure

Open the driver's door and look at the inside edge of the door jamb — you will see a white or silver sticker with tyre information printed on it. This sticker lists the correct pressure for the front tyres and the rear tyres separately, because they often differ. The pressure is given in PSI (pounds per square inch) in the UK and Europe, though some vehicles show both PSI and bar.

If you cannot find the sticker on the door jamb, check the fuel door (on the outside of the car, near the petrol cap), the inside of the glove box, or your owner's manual. Never use the pressure printed on the tyre wall — that number is the maximum pressure the tyre can safely hold, not the pressure your car needs.

How to use a tyre pressure gauge

Remove the valve cap from the first tyre by turning it counterclockwise. Keep the cap somewhere you will not lose it — many people set it on the wheel hub or in their pocket.

Press the gauge firmly onto the valve stem until you hear a small hiss of air. The gauge will show a reading in PSI or bar. If the gauge is digital, the number will appear on a screen; if it is a dial gauge, a needle will point to the number. Write down the reading for each tyre.

Repeat this process for all four tyres, including the spare if your vehicle has one and you want to keep it ready. The front and rear pressures may be different — check your door jamb sticker to see what each should be.

What to do if pressure is too low or too high

If a tyre is under-inflated (lower than the door jamb sticker says), you need to add air. Most petrol stations have air pumps near the forecourt; some are free and some charge 50p to £1. Attach the pump nozzle to the valve stem, set the pump to your target pressure, and let it run. The pump will stop automatically when the tyre reaches the right pressure, or you can stop it manually and check with your gauge.

If a tyre is over-inflated, you need to release air. Press the small pin inside the valve stem with your thumb or a small tool to let air out slowly. Check the pressure every few seconds with your gauge until you reach the target. This takes patience but prevents damage from over-inflation.

If one tyre is consistently low after you inflate it, the tyre may have a slow leak. Drive to a tyre shop or petrol station and ask them to check for a puncture or a faulty valve. A slow leak can be repaired if it is in the tread; if it is in the sidewall, the tyre must be replaced.

How often to check tyre pressure

Check your tyre pressure at least once a month, and always before a long journey. Many people check when they fill up with petrol, since they are at the pump anyway. Pressure naturally drops by 1 to 2 PSI per month as air seeps through the rubber, so monthly checks catch slow leaks before they become dangerous.

Check pressure more often in winter, because cold air contracts and lowers the pressure inside the tyre. A tyre that is at the correct pressure in autumn may be 3 to 5 PSI low by January. Check again when the weather warms up in spring.

Why tyre pressure matters for safety and cost

Under-inflated tyres generate more heat and friction, which wears the tread faster and wastes fuel — a tyre that is 6 PSI below the correct pressure can reduce fuel economy by 3 percent. Under-inflation also makes the steering feel sluggish and can cause the tyre to overheat and fail, especially on a long motorway journey.

Over-inflated tyres ride hard and put all the weight on the centre of the tread, leaving the edges to wear slowly. This uneven wear shortens the life of the tyre and makes the car bounce over bumps. Over-inflation also stresses the sidewall and can lead to a sudden blowout.

The correct pressure balances fuel economy, tyre life, handling, and safety. Checking once a month takes five minutes and costs nothing if you use a petrol station gauge.

Frequently Asked Questions

Should I check tyre pressure before or after I drive?

Check before you drive, or wait at least three hours after you stop. Driving heats the air inside the tyre and raises the pressure by 4 to 6 PSI, so a reading taken after driving will be higher than the true cold pressure. If you inflate based on a warm reading, the tyre will be under-inflated once it cools down.

What if my front and rear tyres have different pressures?

This is normal and correct. Many vehicles need higher pressure in the rear than the front, or vice versa, depending on the weight distribution and suspension design. Always check your door jamb sticker to see the correct pressure for each axle, and inflate each tyre to its own target.

Can I use the gauge at a petrol station air pump instead of buying my own?

Yes, most petrol station pumps have a built-in gauge, and you can check your pressure for free while you inflate. If you want to check without inflating, or if your local pump is broken, a handheld gauge is cheap and lasts for years. Many people keep one in the glove box for convenience.

What does it mean if one tyre keeps losing pressure?

A tyre that drops 2 to 3 PSI between monthly checks may have a slow leak in the tread, which can often be repaired. If it drops more than that, or if the leak is in the sidewall, the tyre will need to be replaced. Take the car to a tyre shop and ask them to inspect the tyre for punctures or a faulty valve stem.