How to check and inflate tyre pressure

Checking tyre pressure is essential for road safety, driver performance, and fuel efficiency. If it’s too high, you run the risk of excessive wear, poor vehicle handling, and low suspension. Too low, and you’ll likely experience punctures, poor fuel efficiency, and increased rolling resistance. Either way, it’s dangerous. So, knowing how to check and inflate your tyres is critical to your day-to-day driving. Here’s everything you need to know.

How to check your tyre pressure

You can use the gauge provided at a petrol stations to check tyre pressures. Usually, you’ll see a machine for air and water with the gauge attached. Otherwise, you can buy an LED tyre pressure gauge.

Next, you should check the recommended tyre pressure measurement for your vehicle (usually measures in PSI or bar). This is typically found in your vehicle handbook, on the dashboard (for newer vehicles), inside the fuel cap, or on the driver’s door. Try the glove box or passenger door side to find the vehicle handbook.

Then, with the gauge and pressure measurement ready, follow these steps to check your pressure:

  1. Before you start, make sure the tyres are cold. If they’re too warm, you may get inaccurate pressure readings.
  2. Remove the valve caps on each wheel.
  3. Insert the gauge onto the valve and push until the hissing sound stops.
  4. Check the PSI reading and compare it to the recommended PSI for your vehicle.
  5. Determine whether you need to increase or decrease the air in your tyres and follow the steps below.
  6. Repeat the process for all wheels.

How to inflate your tyre pressure

If the pressure is too low, follow these steps to inflate the tyres.

  1. Attach the hose fitting to the valve using the tyre pressure gauge and press the lever. Or, if the hose has a screw fitting, screw until tight, so no air escapes.
  2. Turn the inflator on—you should hear air flowing through the hose.
  3. The tyre pressure gauge will stop once it’s reached the correct PSI. If not, keep an eye on the reading so you can control it manually.
  4. Don’t forget to put the valve cap back on. You can then move on to inflating another tyre if needed.

How to release air from tyres

Your tyres may be overinflated if you’ve been carrying excessive weight, such as baggage or towing a caravan. Or you may have simply inflated them too high by mistake. Overinflated tyres are dangerous and can harm your vehicle's performance. So, if the tyre pressure exceeds the recommended PSI, you must deflate them by following these steps:

  1. To release air, use the digital gauge again. If you’re at a petrol station, be sure to use the correct hose. Typically, there’s a hose for inflating tyres and a hose for releasing air. For manual air inflators, you should also have a separate pin specifically for deflating tyres. If not, you may need to order one online to attach it to your device.
  2. Set the gauge to the recommended PSI, then connect it to the valve.
  3. Press down long enough to release air and wait for the machine to beep to tell you when it reaches the correct PSI.
  4. Remember to reattach the valve when complete, or you may lose more air than intended.

Where can I check my tyre pressure?

You can check tyre pressure anywhere with a portable inflator and pressure gauge. Otherwise, you’ll need to visit a petrol station and use the dedicated machine. Of course, you can also book a free tyre check at yourlocal Halfords garage, and we’ll check your tyre pressure for free.

When should your tyre pressure be checked?

You shouldn’t wait for your tyre warning light before checking air pressure. If you’re proactive, you’ll likely stop issues like punctures before they occur. And you’ll also maximise the life of your tyres, saving you further costs down the line.

It’s good practice to check tyre pressure every few weeks. In addition, you should check tyre pressure before and after a long drive, as well as after any sudden temperature changes. In particular, cold weather can cause tyre pressure to drop.

When should I inflate my tyres?

It’s crucial to inflate tyres at the right time. Ideally, tyres should be cold because warm tyres can give an incorrect PSI reading. Plus, handling tyres when hot is not a good idea as you may cause an injury. If you’ve been driving continuously for an hour or so, wait at least two hours for the tyres to cool down.

What is the correct tyre pressure?

There’s no one-size-fits-all approach for tyre pressure. It varies by vehicle, so you’ll need to check the handbook to find the recommended PSI. It might also be on the inside the driver’s door or fuel cap, or digitally on the dashboard. For newer cars, it may tell you the current PSI of each tyre and what they need to be.

What are the effects of low tyre pressure?

Underinflated tyres can cause a range of issues from increased fuel consumption to aquaplaning. As a result, it’s crucial to monitor tyre pressure regularly to avoid these risks and to ensure you remain safe on the road.

Low pressure affects the balance of the vehicle

  • A reduction in pressure on the front axle will tend to increase the chances of understeer.
  • A reduction in pressure on the rear axle will tend to increase the chances of oversteer.
low tyre pressure causing understeer

Understeer: The car turns less than expected

high tyre pressure causing oversteer

Oversteer: The car turns more than expected

Low tyre pressure and the affect on aquaplaning

Michelin conducted tests to see how much of the tyre is in contact with the ground when it was progressively deflated by driving a car through a fluorescent dye on a toughened glass window and photographed the results. As you can see below, the lower the pressure, the less the tyre is in contact with the road. This will dramatically increase the chances of aquaplaning in wet weather.

If the tyre with correct pressures has a nominal surface contact area of 100% then the progressive reduction in contact can be seen.

2 bar tyre pressure

Pressure = 2 bar
Surface contact = 100%

1.5 bar tyre pressure

Pressure = 1.5 bar
Surface contact = 50%

1 bar tyre pressure

Pressure = 1 Bar
Surface contact = 25%

Low tyre pressure and the risk of rapid deflation

Prolonged running at reduced pressure causes a buildup of excess heat in the tyre, and in exceptional cases, can cause the tyre to fail and cause a rapid deflation.

Low tyre pressure and the effect on tyre life

A tyre that is under-inflated by 20% will have a reduction in life of just over 20% (depending on use). This could mean changing the tyres up to 5,000 times sooner than normal.

Conversely, over-inflation will also increase the incidences of abnormal wear and these will be particularly accentuated in the middle of the tyre.

Low tyre pressure and the effect on your fuel efficiency

A set of under-inflated tyres will cause the engine to work harder and this will increase your fuel consumption. A set of tyres that is 10psi under-inflated will have the same effect as increasing the cost of fuel by 4.5p per litre (based on £1.50 per litre). This could lead to needing an extra tank of fuel per year.


Yes, high tyre pressure can be unsafe. It’s tempting to put extra air in your tyres to make them last longer, but it has the opposite effect. Too much air increases the risk of blowouts, excessive and uneven tyre wear, and poor vehicle handling.

Low tyre pressure is a safety hazard for you and other drivers. Underinflated tyres drastically increase the risk of punctures, which can lead to road accidents. Tyres with low air also impact braking performance, fuel consumption, and tyre wear, all of which can lead to decreased tyre life.

Usually, yes, your tyres may need additional pressure with extra weight, such as towing a caravan or trailer. Most vehicles have two recommended tyre pressures—one for regular driving and one for driving with additional loads. You can increase the PSI to this level to help power your vehicle with extra weight. However, after removing the load, you should immediately return the air pressure to normal.

Once you’ve returned the tyres to the correct PSI, the TPMS warning light should go off on its own. If it doesn’t, refer to the vehicle handbook to guide you.

Yes, Halfords will check your TPMS as part of your MOT or service. If you think your TPMS may be faulty, just book your vehicle in, and our technicians will check it thoroughly.

Same day tyre fitting

Did you know that we now offer same day tyre fitting service across our garages nationwide? Simply book online before 1pm and we can replace your tyres the same day to help you get you back on the road safely and swiftly. Please note that availability varies by location. For more information, please head on over to our dedicated same day tyre fitting page where you can find answers to frequently asked questions, choose the right tyres for your vehicle and book your appointment.

Book same day tyre fitting