Tyre pressure: when and how to check yours
Tyre pressure is one of the most frequently neglected checks, and one of the most consequential. Tyres that are under or over-inflated handle differently, wear faster and are more likely to fail. Checking them correctly takes a few minutes and requires nothing more than a pressure gauge.
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Why tyre pressure matters
Tyre pressure directly affects how your car handles, stops and uses fuel. An under-inflated tyre flexes more with each rotation, which generates heat, increases rolling resistance and accelerates wear along the tyre edges. An over-inflated tyre makes less contact with the road, reducing grip in corners and braking, and causes wear concentrated in the centre of the tread.
The effects are not just gradual. A significantly under-inflated tyre can overheat and fail suddenly, while both conditions extend stopping distances - a critical difference in an emergency stop. Fuel consumption also rises measurably with under-inflation, since the engine works harder to overcome the increased rolling resistance.
What is the correct tyre pressure for your car?
The recommended tyre pressure for your vehicle is set by the manufacturer and is specific to the tyre size and load. It is printed in the car's owner handbook and usually on a sticker inside the driver's door frame or fuel cap. Front and rear tyres often have different recommended pressures, and the recommendation changes when the car is carrying a full load.
Pressure is measured in PSI (pounds per square inch) or BAR. Most UK tyre inflators show both. Typical passenger car pressures range from around 28 to 38 PSI for standard loads. Check the sticker for your specific vehicle rather than using a general number.
Check when cold, not after driving
The single most important rule for accurate pressure checks is to measure when the tyres are cold - before the car has been driven, or after no more than 2 miles at low speed. Driving heats the air inside the tyre, which causes the pressure to rise by several PSI. If you check after a motorway run, the reading will be artificially high, and you may actually under-inflate the tyre to reach it.
If you have to check after driving, add 4 to 5 PSI to the recommended pressure as a rough correction, then re-check once the tyres have cooled.
How to check tyre pressure step by step
- Remove the dust cap from the tyre valve stem (keep it safe).
- Press a calibrated pressure gauge firmly onto the valve. If you hear air escaping, the seal is not good - reposition the gauge.
- Read the pressure shown on the gauge.
- Compare it to the recommended pressure in your car's handbook or door sticker.
- If too low, add air using a petrol station inflator or a portable compressor.
- If too high, press the pin inside the valve stem to release small amounts of air, then re-check.
- Replace the dust cap once done.
Check all four tyres, including the spare if your car has a full-size spare rather than a temporary run-flat or foam kit.
The tyre pressure warning light
Since 2014, new cars sold in Europe have been required to include a Tyre Pressure Monitoring System (TPMS). The warning light - usually an exclamation mark inside a tyre cross-section - lights when pressure in one or more tyres has dropped to around 25% below the recommended level.
The TPMS warning does not mean a tyre is flat. It means the pressure has dropped enough to affect safety and fuel economy. Check and inflate all four tyres as soon as you can after the light appears. The light should go out once pressure is restored - if it does not, the TPMS sensor may need resetting or a tyre may have a slow puncture.
How often to check tyre pressure
A monthly check is the practical standard for most drivers. Additionally check before any long journey, when carrying heavy loads or extra passengers, and after a significant temperature drop - cold weather reduces tyre pressure by roughly 1 PSI for every 10 degrees of temperature fall.
Our guide to tyre laws in the UK covers the legal minimum tread depth and what you risk driving on worn or damaged tyres.
Short-term cover for borrowed or recently-bought cars
Checking the tyre pressures is one of the first things worth doing when you get into an unfamiliar vehicle. If you are borrowing a car for the day or have just bought one privately and need to drive it home, temporary car insurance gives you comprehensive cover from the moment you take the keys - and a quick tyre check before you set off costs nothing.
Frequently asked questions
Should you check tyre pressure hot or cold?
Always check when cold - before driving or after no more than 2 miles at low speed. Driving heats the air inside the tyre and raises the reading by several PSI, which can cause you to under-inflate the tyre if you check after a journey.
How often should you check tyre pressure?
Once a month as a minimum, plus before any long journey, when carrying extra load, and after a significant drop in temperature. Cold weather reduces tyre pressure by roughly 1 PSI for every 10 degrees of temperature fall.
What does the tyre pressure warning light mean?
The TPMS light means one or more tyres has dropped to around 25% below the recommended pressure - not that it is flat. Check and inflate all four tyres as soon as possible. If the light does not go out after inflating, the TPMS sensor may need resetting or you may have a slow puncture.
Can you drive with low tyre pressure?
Not safely, and not far. Low tyre pressure reduces grip and increases stopping distances, raises the risk of a blowout, and causes uneven wear. If the TPMS light comes on during a journey, find a safe place to stop and check rather than continuing to your destination.
Where do I find the correct tyre pressure for my car?
The manufacturer's recommended pressure is in the car's owner handbook and usually on a sticker inside the driver's door frame or on the fuel cap. Front and rear pressures are sometimes different, and there is often a separate figure for full loads.
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