Key takeaways
- Find your correct tyre pressure on the sticker inside the driver's door, the fuel flap or in the handbook — not on the tyre itself.
- Always check pressures when the tyres are cold, as driving heats the air and gives a falsely high reading.
- Check at least once a month and before long journeys, and adjust upward when carrying a heavy load or extra passengers.
- Correct pressure improves grip, braking and fuel economy and makes your tyres last longer, according to the Energy Saving Trust.
Tyre pressure is one of the cheapest things to get right and one of the most costly to ignore. Run them soft and they wear at the edges, use more fuel and grip less in an emergency stop; run them hard and the ride suffers and the centre wears. This guide shows you where to find the correct figure, how to check it properly, and how to set it.
How do you check your tyre pressure?
To check tyre pressure, find your vehicle's recommended figure, then use an accurate gauge on cold tyres. Unscrew the valve cap, press the gauge firmly onto the valve until the hiss stops, and read the pressure. Compare it to the recommended figure and add or release air as needed, then refit the cap. Repeat on all four tyres.
- Check when tyres are cold — parked for at least a couple of hours or driven under two miles.
- Remove the valve dust cap and keep it safe.
- Press the gauge squarely onto the valve so no air escapes around it.
- Read the figure and compare with your recommended pressure.
- Top up or release air to match, then recheck and refit the cap.
- Do not forget the spare, if you have one.
Where do you find the correct tyre pressure?
Your correct tyre pressure is set by the vehicle manufacturer, not the tyre maker. Look on the placard inside the driver's door shut, on the fuel filler flap, or in the owner's handbook. It is given in PSI or bar and usually lists separate figures for normal use and for a fully loaded car or motorway driving.
The number moulded into the tyre sidewall is the maximum the tyre can take, not the figure you should run. Always use the vehicle's recommended pressure. Many cars list a higher rear pressure for heavy loads, so match the figure to how the car is actually being used that day.
Why does checking cold matter?
Tyre pressure must be checked cold because air expands as it heats up. Driving warms the tyres and can raise the reading by several PSI, so a hot tyre that reads correct may actually be under-inflated once it cools. Manufacturer figures all assume cold tyres, meaning parked for a couple of hours or driven only a short distance.
If you can only reach a forecourt air machine after a longer drive, expect the reading to be a little high and avoid letting air out to "correct" it — you would end up under-inflated once the tyres cool. Better to check at home with your own gauge first thing.
What happens if your pressure is wrong?
Incorrect pressure costs you in safety, money and tyre life. Under-inflation is the bigger danger: the tyre flexes more, runs hot and can fail, while wearing heavily at both edges. Over-inflation reduces the contact patch, harms grip and wears the centre. The Energy Saving Trust notes that correctly inflated tyres also improve fuel economy.
If your dashboard warning light comes on, the pressure has usually dropped enough to need attention soon. A persistent loss after topping up often means a slow puncture rather than normal seepage.
What gauge should you use?
Any accurate gauge will do, and a personal one is more reliable than a busy forecourt machine. A digital or dial gauge from a motor factor costs only a few pounds and lets you check cold tyres at home, which is the most accurate time. Forecourt machines are convenient but are often knocked about and can read inaccurately.
If you use a forecourt machine, set the target figure, inflate, then check with your own gauge afterwards if you can. Built-in pressure monitoring systems on newer cars help too, but they warn you only once pressure has already dropped, so they are no substitute for a manual check.
Should you adjust pressure for a load?
Yes. Carrying extra passengers, a full boot or a roof load increases the weight the tyres support, so they need more air to keep their shape and avoid overheating. Most cars list a separate higher pressure for a full load, usually applied to the rear or to all four, on the same placard as the standard figure.
Remember to return to the normal pressure once the load is gone, otherwise the tyres run over-inflated, harming grip and wearing the centre. Towing a caravan or trailer also calls for the laden figure, and the trailer's own tyres must be set to its plate.
| Situation | What to do |
|---|---|
| Everyday driving, light load | Use the standard recommended pressure |
| Full car or heavy boot | Use the higher "fully laden" figure |
| Long motorway journey | Set to the laden figure, check cold beforehand |
| Warning light on after topping up | Suspect a slow puncture — get it checked |
Pressure light staying on?
If the pressure looks right but the warning light stays on, the issue may be a faulty sensor or a slow leak rather than the air itself. Our guide on why your tyre pressure light is on explains the causes, and if you suspect a leak, a slow puncture is a common culprit. Either way, Fast Tyre can come to you: our puncture repair service finds and fixes leaks at your home or roadside across London and central England, so you are not left guessing at a forecourt.
Frequently asked questions
At least once a month and before any long journey. Tyres lose a little air naturally over time, so a monthly check keeps them at the right level. Also check whenever you load the car heavily or notice the handling or ride feeling different.
Always check cold, meaning parked for a couple of hours or driven under two miles. Air expands as it warms, so a hot tyre reads higher than it really is. Manufacturer pressures all assume cold tyres, so checking warm can leave you under-inflated.
Use the figure on the placard inside the driver's door, the fuel flap, or in your handbook — not the number on the tyre sidewall, which is the maximum. Many cars list a higher pressure for a full load or motorway driving, so match it to your use.
Yes. Over-inflation shrinks the contact patch, reducing grip and braking, gives a harsher ride and wears the centre of the tread faster. Stick to the vehicle's recommended figure rather than the maximum on the sidewall, adjusting up only when carrying a heavy load.
A small monthly loss is normal seepage. A faster or repeated drop after topping up usually means a slow puncture, a damaged valve, or a corroded wheel rim. If it keeps falling, have the tyre inspected rather than topping it up again and again.
Yes. Under-inflated tyres increase rolling resistance, so the engine works harder and uses more fuel. The Energy Saving Trust highlights correct pressure as a simple way to improve economy, and it also helps your tyres last longer and wear evenly.