Check your tyre pressures at least once a month, and always before a long journey. Even healthy tyres lose air gradually through the rubber and valve, and a small drop hurts grip, economy and tyre life long before you'd notice it from behind the wheel. A five-minute check beats discovering the problem at the roadside.
Why monthly?
Tyres can lose a small amount of pressure every month just through natural permeation, and more in cold weather. A tyre that's a few PSI low won't feel dramatically different, but it wears unevenly, uses more fuel and is more prone to overheating. That's why tyre-safety charity TyreSafe recommends a monthly check as a minimum for every driver. Monthly is frequent enough to catch a gradual loss before it matters, without being a chore.
Don't rely on the TPMS alone
A TPMS is a safety net, not a substitute for checking. Many systems only warn once a tyre is significantly low, often around 20% under (the threshold UK and EU cars are approved to), by which point you've already lost performance and worn the tyre. Some indirect systems can also be fooled by a gradual loss across all four tyres at once, because they work by comparing wheel speeds. A monthly manual check catches problems far earlier than the warning light ever will.
When to check more often
Monthly is the baseline, but some situations call for an extra check:
- Before any long or motorway trip.
- When the car is heavily loaded (use the laden pressure figure).
- After a big temperature change, see cold-weather pressure.
- If you suspect a slow puncture.
- After hitting a pothole or kerb that might have damaged a tyre.
How to check properly
Always check when cold, before driving or after no more than a mile or two, using an accurate gauge, and don't forget the spare if you have one. Set each tyre to the figure on your door placard, not the maximum on the sidewall, and refit the valve caps to keep dirt out. It takes five minutes and saves money, fuel and tread. A small digital gauge of your own is worth having, since forecourt machines can drift out of calibration.
What low pressure costs you
Running even a few PSI low has a real, ongoing cost. Under-inflated tyres flex more, which raises rolling resistance and pushes up your fuel bill every mile. They wear faster and unevenly on the shoulders, shortening their life. And the extra flexing builds heat, which is a common cause of a blowout. So the monthly check isn't just about avoiding a flat, it quietly protects your fuel economy, your tyre life and your safety all at once, which is a lot of return for two minutes at a fuel stop.
A simple monthly routine
The easiest way to make a monthly check happen is to tie it to something you already do, such as the first fuel fill of the month. It takes five minutes at a forecourt, and less on your own driveway with a digital gauge.
| Step | What to do | Common mistake |
|---|---|---|
| 1 | Find the placard figure for your tyre size and load (door shut, fuel flap or handbook). | Using the maximum pressure moulded on the tyre sidewall. |
| 2 | Check cold: before driving, or within a mile or two of home. | Checking after a motorway run, when readings are a few PSI high. |
| 3 | Remove the cap, press the gauge on squarely and read it. Repeat if you heard air escape. | Trusting one reading from a forecourt machine nobody has calibrated. |
| 4 | Inflate or release to the exact figure. Do all four, then the spare. | Leaving the spare for "next time". |
| 5 | Refit the caps. Note any tyre that needed more than a couple of PSI. | Ignoring a tyre that is always the low one. |
A tyre that is consistently lower than the other three at every monthly check is not "just losing air". It has a slow puncture, a leaking valve or a corroded rim seal, and the longer it runs low the more tread it wastes. Have it looked at rather than topping it up for another month.
Temperature and the seasons
Tyre pressure falls as the air inside cools, so the first cold snap of autumn is when the most tyres are quietly under-inflated. As a rule of thumb, a tyre loses roughly 1 PSI for every 5 to 6°C drop in temperature, on top of the natural loss through the rubber.
A car set correctly on a warm September afternoon can be several PSI down on a frosty November morning without any leak at all.
Two habits deal with it. Check pressures whenever the weather changes markedly, not only on the calendar date, and always check in the cold part of the day. A tyre parked in low winter sun on one side of the car can read higher than its partner in the shade, so early morning is the most consistent time.
The effect works in reverse in summer. Tyres set in a cool garage and then driven hard on a hot motorway read well above the placard figure when warm, which is normal; do not let air out of a hot tyre to bring it "back down".
Gauges, forecourt machines and TPMS resets
A cheap digital gauge of your own is the single best tool for the job, because forecourt machines vary and you have no way of knowing which are accurate. Keep it in the door pocket, check it once against a machine you trust, and use it consistently so that your readings at least compare with each other month to month.
Forecourt machines are fine for adding air. Set the target pressure, wait for the beep, then confirm with your own gauge.
If the machine and your gauge disagree by more than a PSI or two, trust the gauge you know. Some machines on busy forecourts leak at the chuck, which shows as a hiss and a reading that will not settle.
After adjusting pressures, some cars need the TPMS to be reset through the menu or a button, especially indirect systems that learn wheel speeds. If the light stays on after a correct top-up, check the handbook for the reset procedure before assuming a fault.
Direct systems with a sensor in each wheel usually clear the warning after a short drive.
Electric cars, vans and heavy loads
The heavier the vehicle, the more a few PSI matters, which puts electric cars and vans at the top of the list for a strict monthly check. An EV carries a battery pack that adds hundreds of kilograms, and its tyres usually run at a higher pressure to cope.
Under-inflated EV tyres wear the shoulders quickly and cost range, because rolling resistance rises as the tyre flexes more.
Vans have the same problem with a variable load. A van run empty at the laden figure rides hard and wears the centre of the tread; the same van loaded to the roof on the unladen figure overheats the tyres. If you drive a van for work, check pressures against the load you are actually carrying that week.
Anyone who tows should check the caravan or trailer tyres before every trip rather than monthly, because they sit for weeks between uses and lose air unnoticed. UK tyre law and the basic checks every driver is expected to make are summarised on GOV.UK.
