- Why tyre pressure checks matter for every driver
- How often to check your tyre pressure
- Finding the right tyre pressure for your car
- Step by step: checking tyre pressure with a gauge
- Reading the pressure units: psi, bar and kPa
- What the tyre pressure warning light means
- Tyre pressure and the rest of your tyre checks
- Sharing your tyre and car knowledge
- Frequently asked questions
To check tyre pressure, use a reliable gauge on cold tyres and compare each reading with the vehicle maker's recommendation, found in the handbook, fuel filler cap or driver's door sill. Check at least monthly and before long journeys, and raise the pressure if the car is heavily loaded.
Most of us glance at the fuel gauge without a second thought, yet the four patches of rubber holding the car to the road get ignored for months. Tyre pressure drifts down slowly, so nothing feels wrong until braking or steering starts to feel a bit off.
I've pulled this guide together from the TyreSafe charity's advice, the Highway Code's vehicle maintenance annex on GOV.UK and the AA's dashboard warning light guide. Your car's handbook always has the final word, because the right numbers differ from one model to the next.
Why tyre pressure checks matter for every driver
The Highway Code says tyres must be inflated to the vehicle manufacturer's specification for the load being carried, and that incorrect pressure affects braking and steering. TyreSafe adds that both under-inflation and over-inflation make handling and grip worse.
Air also leaks out gradually through the tyre and valve, and a small puncture can go unnoticed for days. A quick look with a gauge catches that early, before the tyre is damaged.
How often to check your tyre pressure
The advice differs slightly depending on who you ask, so here's what the two sources I read say:
- TyreSafe recommends checking at least once a month and before any long journey.
- The Highway Code goes further and suggests checking pressures weekly, before your journey, when the tyres are cold.
- Weather matters too. TyreSafe gives a rule of thumb that pressure changes by about 1.5psi (0.1 bar) for every 10 degrees Celsius change in the surrounding temperature, which is why a cold snap can trigger a warning.
Finding the right tyre pressure for your car
This is where people go wrong. The number moulded into the tyre sidewall is a limit for the tyre itself, not your target. Your target comes from the vehicle maker.
- Look in the vehicle handbook first.
- TyreSafe says the information is also available inside the fuel filler cap or on the driver's door sill.
- A tyre retailer can look up the numbers for you if you can't find them.
- Many cars list different numbers for the front and rear tyres, and for a normal or heavily loaded car, so read the whole label.
The Highway Code and TyreSafe both say to increase the pressure if the vehicle is heavily loaded, as shown in the car maker's recommendations. Think holiday luggage and a full back seat.
Step by step: checking tyre pressure with a gauge
A reliable gauge is the one thing you need. Plenty of petrol stations have air machines with a built-in gauge, and you can also buy a small hand gauge. The Highway Code says warm or hot tyres can give misleading readings, so aim to check before driving or after only a very short trip.
- Park on level ground and find the recommended numbers in your handbook, fuel flap or door sill.
- Unscrew the dust cap from the first tyre valve and keep it somewhere safe.
- Press the gauge firmly onto the valve until the hissing stops and read the number.
- Compare it with the recommended pressure for that tyre, at the right load.
- If it's low, add air in short bursts and re-read after each one. If it's high, release a little air by pressing the pin in the valve centre.
- Refit the dust cap, then repeat for every tyre.
TyreSafe also says to check the spare, or the compressor and sealant if the car doesn't have a spare wheel. It's easy to forget until the day you need it.
Reading the pressure units: psi, bar and kPa
Gauges and labels can use different units, which looks confusing. The same target may be shown in more than one way, so match the unit on your gauge to the unit on your label. TyreSafe's own example of a standard pressure is 35psi, which it gives as 2.4 bar.
| Unit | Where you'll see it | Quick note |
|---|---|---|
| psi | Garage air machines and many handbooks | The unit most UK drivers know |
| bar | Fuel flap stickers and many gauges | TyreSafe's example: 35psi is shown as 2.4 bar |
What the tyre pressure warning light means
Some cars have a dashboard light that warns you when pressure drops. The AA says an amber tyre pressure light means pressure is getting low and the tyres may be underinflated. It says you can carry on only to complete your journey or drive to a garage.
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The AA's advice is to check your dashboard, which may show which tyre is affected, inflate it and carry on. If the light comes back, you probably have a slow puncture and the tyre needs replacing. Ignoring it risks tyre failure and reduced steering control.
Tyre pressure and the rest of your tyre checks
While you're at the wheel with the gauge, take a minute to look at the whole tyre. TyreSafe recommends checking for cuts, bulges and visible damage on the sidewalls and tread. It also covers the tread itself: the legal minimum for cars is 1.6mm, and TyreSafe says to consider replacing tyres once the tread falls below 3mm. I've explained how to measure that in this guide to checking tyre tread depth.
Oil is the other quick check that tends to get put off. The same level-ground habit applies, and checking the engine oil only takes a few minutes with a dipstick.
Sharing your tyre and car knowledge
If you've got a good eye for tyres, servicing and everyday car care, there's a place to put it to use.
Motoring writers can look through car blogs that accept contributor articles on my pitching page.
Frequently asked questions
How often should I check my tyre pressure?
TyreSafe recommends at least once a month and before any long journey. The Highway Code suggests weekly checks, before your journey, when the tyres are cold.
Where do I find the correct tyre pressure for my car?
Check the vehicle handbook first. TyreSafe says the information is also inside the fuel filler cap or on the driver's door sill, and a tyre retailer can tell you too.
Should I check tyre pressure when the tyres are hot or cold?
Cold. The Highway Code says warm or hot tyres can give misleading readings, so check before you drive or after a very short trip.
Do I need more pressure when the car is full of luggage?
Often, yes. The Highway Code and TyreSafe both say to increase pressure for a heavily loaded vehicle, following the car maker's recommendations in the handbook.
Is the pressure on the tyre sidewall the one I should use?
No. That number is a limit for the tyre, not your target. Use the pressure the vehicle maker recommends for your car and load.
