Tyre pressure check

Tyre pressure is important for your safety, how your car drives and its fuel economy. Make sure you check yours regularly to keep your car running smoothly.

If you want to know how to check your tyre pressure yourself, follow our expert guide below.

How to check tyre pressure

The best way to check your tyre pressure is by using a good-quality, accurate tyre pressure gauge. Here’s how to do it step-by-step:

1. Check your recommended PSI

First, you'll want to know what PSI your tyres should be – PSI stands for pounds per square inch, which is the unit of measurement used for air pressure within tyres.

• Check the manufacturer’s recommended PSI before you start so you’ll know if any tyres are under (or over) inflated

2. Remove the valve cap and insert the pressure gauge

• Remove the valve cap from one tyre
• Press the pressure gauge onto the valve stem until the hissing sound stops and the gauge gives a reading
• Write down the reading for the tyre
• Repeat for the other tyres

3. Let air out if necessary

• If tyres are over-inflated, you can let air out of them
• Inside the valve stem is a metal pin – press this with a screwdriver to let air out. Or, if you only need to let out a small amount of air, you can use the pressure gauge. Apply the gauge to the valve, but not fully, so that the hissing air can be heard. You can then periodically reseal the gauge to the valve to recheck the pressure. Keep doing this until you reach the desired pressure

4. Refill with air if necessary

This is how you can put air into your tyres:

• If any tyres are under-inflated, use an air-compressor to refill them
• Press the air compressor hose onto the valve stem (or screw the hose to the valve if you have that type of air compressor) and fill until the right PSI (as per your car’s manufacturer) is shown on the gauge
• Some digital air compressors allow you to set the pressure before you start using the compressor. Set the desired pressure and the compressor will either beep our cut out when that pressure is reached

What is the correct tyre pressure for my car?

Your vehicle handbook will tell you what pressure you should have in your tyres (or where to find the sticker that tells you, inside your car). 

Often you’ll find a small sticker with the tyre pressures on too – usually inside the fuel filler flap or on the drivers’ door edge.

It'll give you a figure in pounds per square inch (PSI) or BAR pressure. BAR is the metric unit of atmospheric pressure equal to 14.50 pounds per square inch.

• Pressures are given for cold tyres (ones that haven’t been driven for at least 2 hours)
• There are usually two figures, one for 'normal' use and a higher figure for full loads

If you can't find the correct tyre pressures, contact the vehicle manufacturer’s customer services team. You’ll need a note of:

• The size of the tyres fitted, taken from the sidewalls
• The make, model and registration number of your vehicle

Read what to do if your tyre's gone flat:

• How to change a flat tyre

When should tyre pressure be checked?

You should only check your tyre pressure when the tyres are cold. ‘Cold’ means that the car hasn’t been driven for a couple of hours.

The pressure inside your tyres increases as they heat up. If you set your pressures when your tyres are already warm, their pressure will probably be too low.

If you’re driving to a garage or petrol station to check your tyres, try to go at the start of your journey to one that’s only a short drive away. That way, your tyres won’t heat up too much. If you go in the middle of a long journey, your tyres will be warm which will affect the pressure reading.

How often should I check tyre pressure?

Aim to check your tyre pressures every couple of weeks.

Makes sure the tyres are cold and use a reliable tyre pressure gauge.

Where can I check my tyre pressure for free?

Some of the big chains of garages and tyre shops offer a free tyre-checking service where they’ll also check your tyre pressures. 

Otherwise, many petrol stations have a coin-operated tyre pressure pump near the forecourt. You can check your pressure and top up with air for the price of a few coins in loose change.

What happens if my tyre pressure is too high or low?

It could be dangerous to drive with the wrong tyre pressure as it can affect stopping distances, severely affect the vehicle's handling, or make a blow-out more likely.

Plus, under or over inflation increases tyre wear so you’ll have to buy new tyres more often.

Dangers of under-inflated tyres

• Tyres will flex more and get hotter, making sudden tyre failure (blowouts) more likely
• Under inflated tyres will increase stopping distances and affect your vehicle’s handling, making collisions more likely
• Tyres will wear more on the edges of the tread
• Increases your tyre’s rolling resistance which means higher fuel consumption

Low or uneven tyre pressure can also cause steering problems. 

Dangers or over-inflated tyres

• Tyres will wear more in the centre of the tread
• Less contact area with the road which can cause a loss of traction
• Increased stopping distances

Higher pressures can mean a harsher more uncomfortable ride, but don’t be tempted to reduce pressures for a softer ride.

Other ways to care for your tyres

Taking care of your tyres is one way to make sure you’re driving safely and efficiently and avoid a breakdown.

• Take a bit of time to check the tread for wear and also to look for cuts, or bulges on the sidewalls. You can check the front tyres more easily by turning the steering from lock to lock
• Get any cut you find checked out by a tyre specialist
• A bulge means the tyre’s got internal damage and must be replaced
• Consider tyre rotation (moving your front tyres to the rear and vice versa) to help keep tyre wear consistent and get the best duration of use out of your tyres

Some elements of your tyres will be checked as part of the MOT test, so it’s especially important to check the tread and get any cuts looked at before you book an MOT.

Find out more about tyre care.

When would you increase the pressure in your tyres?

We recommend that you check your tyre pressures every 2 weeks using a tyre pressure gauge – that way you’ll know if your tyres and under-inflated and you can add air accordingly. Additionally, it helps to increase the pressure in your tyres if you’re going to have a heavy load in your car, or you’re going to tow a trailer – this will allow the full weight of the car to be supported properly.

It’s also worth increasing your tyre pressure in the winter, and decreasing it in the summer (only if it has stayed at a consistent high level by the end of winter).

How do you know if your tyre needs air?

There are a few signs to look out for either by simply checking over your car or while you’re out for a drive. These include:

• Check the tyres, do they look flat or under-inflated? If they’re noticeably getting flatter, then prioritise getting more air into the tyres ASAP
• Changes in your driving experience – if you hear strange sounds from underneath your vehicle, the steering wheel shaking while you drive, or it’s a struggle to reach certain speeds, make sure to check the pressure of your tyres while diagnosing the problem
• An increased stopping distance – under-inflated tyres won’t grip the road as well, causing you to have a slower stopping time. This can be dangerous, especially when you’re used to your car stopping within a certain distance
• The temperature has suddenly dropped – if it suddenly gets cold out, this can trigger a loss of pressure in your tyres. Check the pressure whenever there are sudden changes in the weather

Is 40 PSI a good tyre pressure?

There is no ‘one-size-fits-all’ tyre pressure. Ultimately, it’ll depend on your car's specific make, manufacturer, or tyre size. In general, 40 PSI is considered on the higher end of the tyre pressure scale though, and wouldn’t typically be suitable for passenger vehicles.

Should front and rear tyre pressure be the same?

Not necessarily, you may find that your vehicle owner’s manual recommends different tyre pressures for the front and rear wheels. This is usually because one end of your car is heavier than the other. The front wheels typically take more of the weight from the engine and therefore might have a slightly lower tyre pressure (this helps with performance and handling).