Check tyre pressures before a long journey

What you will do: Check all four tyres against the manufacturer’s recommended cold pressure, adjust as needed, and inspect the spare wheel or repair kit.

How long it takes: Around 10 to 15 minutes.

Difficulty: Easy. No mechanical knowledge required.

Rough cost: Free to about £1 at a petrol station air machine, or nothing if you own a digital gauge.

This guide is collated from multiple industry sources including Michelin UK, TyreSafe, Blackcircles and National Tyres, and cross-referenced for consistency. It has not been verified against any single manufacturer’s owner’s manual. Your handbook is the primary authority for your car.

Safety first

Only check pressures on cold tyres. A tyre that has been driven on, even briefly, heats up and raises its internal pressure by 2 to 4 PSI. If you adjust to the target figure on a hot tyre, the tyre will be underinflated once it cools. Check before the first drive of the day, or after the car has been parked for at least three hours.

If a TPMS warning light appears while driving, do not ignore it. Pull over somewhere safe as soon as you can and check whether you have a tyre failure or significant air loss. TPMS stands for Tyre Pressure Monitoring System, a sensor that alerts you when pressure drops below a set threshold. All cars manufactured since 2014 are required to have one, and a faulty system will cause an MOT failure.

Underinflated tyres are more likely to suffer sudden rapid deflation and will wear prematurely on the outer edges. TyreSafe estimates that over half the tyres on British roads are underinflated, with 35% running at least 8 PSI below the manufacturer’s recommendation. That is not a minor issue.

What you need

Tools and consumables:

  • A tyre pressure gauge. A digital gauge costs roughly £10 to £30 at most motor factors or online retailers. No primary national price source was available at time of writing, so check current retail prices before buying.
  • Access to an air source. A petrol station air machine typically costs up to about £1 per use, with some supermarket forecourts offering it free. Note that the pricing quoted by Watling Tyres dates from October 2022 and may have changed. Some tyre retailers including Halfords and National Tyres offer free pressure checks in store.
  • Your car’s owner’s manual or the door frame label (more on this below).

A note on petrol station gauges: Some sources suggest that forecourt machines can lose accuracy through heavy use and infrequent calibration. This claim is widely repeated but has not been verified by a primary authority. A personal digital gauge gives you a reading you can trust. That said, many drivers rely on forecourt machines without problems.

Check your car first

There is no single correct tyre pressure that applies to every car. The right figure depends on the vehicle, the tyre size, and how heavily the car is loaded. Front and rear tyres often require different pressures.

Find your car’s recommended pressures in one of three places:

  1. A label inside the driver’s door or door frame (the most common location).
  2. Inside the fuel filler flap.
  3. The owner’s manual.

Ford UK confirms these same three locations for its vehicles. LeaseCar UK covers the same ground for cars generally.

If you cannot find the label, registration number lookup tools are available free at TyreSafe, Just Tyres and Kwik Fit.

The label will usually show two sets of figures: a standard pressure for normal use and a higher loaded pressure for when the car is carrying extra passengers or luggage. Pressures are given in bar or PSI. One bar equals 14.50 PSI, so they are simply two ways of expressing the same thing.

If you drive an electric vehicle, note that manufacturers typically recommend higher pressures to account for the additional weight of the battery pack. Follow your specific vehicle’s figures, not a general rule.

Numbered steps

  1. Look up the correct pressure before you start. Note both the standard and the loaded figures. If you are setting off on a long trip with a full car, use the loaded figure.
  2. Check that the tyres are cold. The car should not have been driven for at least three hours, or you should be checking before the first drive of the day.
  3. Remove the valve cap from the first tyre. The valve is the small rubber or metal stem protruding from the wheel rim. Keep the cap somewhere you will not lose it, such as a pocket.
  4. Connect the gauge to the valve. Press the gauge head firmly onto the valve stem and push until the hissing sound stops. A digital gauge will display the reading immediately.
  5. Compare the reading to your target figure. If the reading is low, add air. If it is high, press the small pin inside the valve to release air in short bursts, then recheck.
  6. Recheck after adjustment. Pressure can change slightly as you attach and detach the gauge. Confirm the final reading before moving on.
  7. Replace the valve cap. The cap keeps dirt and moisture out of the valve.
  8. Repeat for all four tyres, then check the spare or inspect the repair kit (see troubleshooting below).

Check it worked

Once you have checked and adjusted all four tyres, start the car and confirm that the TPMS warning light is not illuminated. On many cars you will also need to reset the TPMS manually after inflating the tyres. Your handbook will explain how, as the procedure varies by manufacturer.

If the light stays on after you have inflated the tyres and completed a reset, the TPMS sensor itself may have a fault. A faulty TPMS will fail the MOT, so have it looked at before your next test.

Troubleshooting

The spare wheel or repair kit

Do not forget the spare. A spare tyre can lose pressure while sitting unused. Check it as part of the same routine. If your car has a full size or space saver spare, it must meet the same legal standards as the other four tyres, including the minimum 1.6 mm tread depth required by UK law.

Space saver spares typically carry speed and distance restrictions. The commonly quoted limits are 50 mph and 50 miles, but these are general guidelines only. Check your handbook for the figures that apply to your car.

If your car has a tyre inflation kit instead of a spare, check that the sealant canister is within its expiry date. These kits are designed for a single use on a small tread area puncture. They will not work on sidewall damage or large punctures. UK law does not require you to carry any puncture equipment at all, so whether you have a spare wheel or a kit is down to what your car came with.

A tyre that keeps losing pressure

If you inflate a tyre and it deflates again within a day or two, you likely have a slow puncture, a faulty valve, or a tyre fault. Check the tyre visually for cuts, tears, embedded objects or uneven wear. If nothing obvious is visible, take it to a tyre shop. Do not keep re-inflating and hoping for the best.

Do not attempt to repair a run-flat tyre yourself. Most tyre manufacturers state that run-flat tyres should not be repaired after deflation and must be replaced.

When to call a professional

Stop and get professional help in any of these situations:

  • A tyre is visibly damaged, bulging, or has something embedded in the sidewall.
  • The tyre keeps deflating after you have inflated it correctly.
  • The TPMS light stays on after inflating and resetting.
  • You are unsure about the condition of the tread. UK law requires a minimum of 1.6 mm of tread across the central three quarters of the tyre width and around the full circumference. Driving on an illegal tyre can mean a fine of up to £2,500 and three penalty points per tyre.
  • Your car has run-flat tyres that have suffered a deflation.

A proper puncture repair carried out to the British Standard (BS AU 159), which involves removing the tyre, inspecting it internally and fitting a combination plug and patch, costs roughly £25 to £45 in London based on figures from June 2026. Prices outside London were not available from a primary source at time of writing, so ask for a quote locally.

Many tyre retailers including Halfords and National Tyres offer free pressure checks if you would rather have someone cast an eye over your tyres before a long trip. That is a reasonable thing to do if you have any doubt at all.

TyreSafe estimates that the UK wastes around £1 billion worth of fuel annually due to underinflated tyres. That figure is a TyreSafe estimate based on DfT and OEM data, not an official government statistic, but the direction is clear. Soft tyres cost you money at the pump and wear out faster. Ten minutes before a long journey is a reasonable trade.

There were 5,594 convictions for defective tyres in 2024, according to TyreSafe citing Criminal Justice System statistics. Most of those are avoidable with a basic check.

What to do next: Before your next long journey, find the pressure label on your door frame tonight. Note the standard and loaded figures. Check all four tyres cold in the morning before you set off. It takes less time than filling up with fuel.