How to check tyre pressures

By David Sholicar

Research undertaken by Protyre has shown that 90% of all vehicles that visit our centres have the incorrect tyre pressure – even for tyres that aren’t being replaced. If you're wondering, “What tyre pressure do I need?” read our guide to find out how to check.

The RAC Foundation commissioned research which found that 2 million drivers never checked their tyre pressures between visits to a garage.
Tyres by their nature leak, this means that over a period of time they will deflate. The speed of deflation will reduce if Nitrogen is used to fill them, however, even if they have been filled with Nitrogen, they will still lose pressure at a slower rate.
Over inflating your tyres can also have a negative effect on the life of your tyres and under inflation will have an impact on the fuel efficiency of your vehicle, in addition to the possible safety implications of either over or under inflation.

How often should you check tyre pressure?

It is recommended that you check your tyre pressures at least once a month and before a long journey or more regularly if you are driving substantial distances on a regular basis.

What should my tyre pressure be?

If you’re unsure what car tyre pressure you should have, it will normally be displayed in one or more of the following three places:

  1. Inside the driver's door on the ledge

  2. Inside the petrol / diesel cap

  3. In the vehicle manual

Alternatively, call your local Protyre and we will be pleased to help.

How to check tyre pressure using a pressure gauge

Low cost tyre pressure gauges are available to purchase from most automotive parts and accessories retailers, from Road Safety organisations such as the AA or RAC or from some tyre manufacturers including Michelin. You should remember that these may be calibrated when you first purchase them, however, these will become less accurate over a period of time.
You should always check tyre pressures when the tyres are cold. When the air in a tyre heats up, it will expand and the pressure will change, giving a higher reading.
Remove the dust caps from your wheels – keep these safe and don’t put them onto the ground as this may get dirt into them and onto the threads, causing them to become more difficult to screw on and potentially damaging the valve.
Attach the pressure valve – check the reading and deflate or use a pump to add additional air as necessary.
When you are satisfied that you have the correct tyre pressure remove the air line from the pump and recheck the pressure.
Replace the dust caps having ensured that no dirt has got into the caps or the air valve.

How to check tyre pressure at a petrol station

You may want to check your tyre pressures when you are refuelling, and most filling stations have machines in place to do this. Using the air pumps available on most forecourts, you can check your tyre pressure and refill if needed. However, it is worth noting that these may not be calibrated and may not give a completely accurate reading. If in any doubt, ask the forecourt attendant when they were last calibrated.
If you have any questions such as what is my tyre pressure? or you would rather have one of our technicians undertake a check, please don’t hesitate to call into any of our centres and we will be pleased to help.
All reputable garages will be happy to check your tyre pressures without charge.

What should tyre pressure be?

If you're worried about asking, “What's my tyre pressure?” rest assured that many other motorists struggle with this. Any reputable garage will be happy to take a look, helping you to understand how and where to look for the correct pressure for your vehicle and tyre combination.

What's my tyre pressure? Bar v PSI

Tyre Pressures are measured in 2 ways:

  1. Bar which is equivalent to 14.5038 PSI

  2. PSI – pounds per square inch

Your tyre pressure can be measured in either Bar or PSI, and tyre pressures are normally shown in both formats. Be cautious do not inflate your tyres to the PSI level if using the Bar scale on your pressure monitor!

Tyre Pressure Monitoring Systems (TPMS)

Since November 2012, Tyre Pressure Monitoring Systems (TPMS) have been legally required on any vehicle sold in the European Union. Many cars sold before this time had TPMS fitted. TPMS systems work on a range of different systems and should you have a problem, a warning light will normally flash on your dashboard.
Of course, tyre pressure monitoring systems first appeared in the luxury marques some time ago. In the late 1980s, Porsche 959 models started to feature it, but at first, it was confined to these high-end and performance cars. Even in those early days, our tyre professionals were working with these systems, gaining the years of experience that they now use every day, on every kind of vehicle.
Bridgestone, Falken, Pirelli and Sumitomo all produce run-flat tyres, that will continue in service even though pressure has been lost. Our qualified fitters can advise on the use of run-flat tyres with TPMS and give specific advice for the make and model you drive and the type of tyres you want to fit.

Note that a faulty TPMS system, or one that doesn’t work at all, will lead to an MOT failure. The Government’s Driver and Vehicle Standards Agency (DVSA) has a useful reference checklist of the MOT tests [1], including the test for a working TPMS for any vehicle used on or after 01/01/2012.
The Royal Society for the Prevention of Accidents (ROSPA) makes the important point that you need to know how the TPMS will tell you if there is a sudden loss of pressure. So, if you have a new car, make sure you will recognise the light, sound or warning that the TPMS on your model uses to alert you to a problem. If you’re not sure or have any queries, why not call in and ask one of the qualified fitters at your local Protyre garage. We have extensive experience with all types of car TPMS and will be happy to help.
If you do find you have a TPMS warning light, you should stop when it is safe to do so and check that you have not had a tyre failure or major leak of air from your tyres. You should contact a garage or fast fit centre as soon as possible to ensure there are no problems with your tyres.

What tyre pressure?

Tyres are your only connection with the road. In fact, at any time each tyre will only have an area the size of the average palm in connection with the road. Apart from tyres and the pressures being important to safety, incorrect tyre pressures will have a number of other effects which may be harmful to your wallet. If you're still unsure how to check tyre pressure, you should call into your local Protyre garage, and our technicians can answer any questions such as what should your tyre pressure be?

Uneven tyre wear

Tyres are built to have as much of their surface in contact with the road as possible. An over or under inflated tyre will wear unevenly, reducing the overall wear in one area of the tyre, reducing its lifespan and meaning that it will need to be replaced more quickly.
Tyres that are incorrectly inflated are also likely to be less fuel efficient and are more likely to suffer from either a blow out or other sudden deflation. Get a free tyre check with Protyre for peace of mind and ensure that you and your passengers are safe.

Tyre life and how tyre pressure affects it

It is very important that each tyre is correctly inflated to get the maximum life out of your tyres. Having the correct tyre pressure helps to make sure that the weight of the vehicle is distributed equally across the tyres' tread pattern, this will ensure that the vehicle is at its most stable. When a tyre is under inflated, it will impact the stability of the vehicle and you will also see a negative impact on the handling and cornering of the vehicle. See also our article on how to identify the age of your tyres.

10 Things to Remember About Tyre Pressures

  1. Tyres should be cold when you check tyre pressures – ideally, they shouldn’t have driven more than 3 miles

  2. Tyre Pressures should be checked at least monthly, more often if you are driving long journeys or are driving a high mileage

  3. Check and change the tyre pressures if you are driving a heavily laden vehicle – always check the handbook or consult your garage

  4. Get the correct pressure details from either the vehicle handbook, driver’s door sill or filler cap

  5. Check that any pressure gauge you use is reliable and has been calibrated recently

  6. Don’t forget to check the spare when you check your pressures

  7. Pressures decrease more rapidly in warmer weather so check more often

  8. If you are towing, don’t forget to check the pressures and adjust accordingly

  9. Use your regular pressure check to check the general condition of your tyres

  10. If in doubt, consult your garage or fast fit centre or call Protyre

General tips for taking care of your tyres

  • Make sure you check the pressure regularly

  • Check for damage on a regular basis and any unusual wear and tear

  • Check your tyres' tread – remember the minimum legal requirement is 1.6mm of tread

  • Don't overload your car

  • When there is extra weight in your car, make sure the tyres are inflated to the recommended levels indicated in the user manual

  • Maintain good driving habits

Tyre fuel efficiency

With the cost of fuel always seeming to be increasing, it is always worth looking for ways to make savings through other areas. Looking at your vehicle's fuel consumption is one such way, as using less fuel ultimately saves money, and various car tyre features can contribute to this factor. Every part of a tyre has the potential to cause a significant increase or decrease in the use of fuel.

Choosing the Right Tyre Made Easy

When it comes to your car's safety and performance, tyres can play a huge role. That's why we've put together a collection of helpful articles to guide you through the process of selecting the perfect tyres for your ride and maintaining your vehicle in general.

If you're looking for a smoother, more luxurious driving experience, premium car tyres might be the way to go. Or, if you want added security against flats, run flat car tyres could be your best bet. Trying to decide between summer car tyres and winter car tyres? We've got you covered there, too.

We also dive into the world of tyre brands, comparing top manufacturers like BF Goodrich tyres, Bridgestone tyres, Continental tyres, Dunlop tyres, Falken tyres, General tyres, Goodyear tyres, GT Radial tyres , Hankook tyres, Michelin tyres, Pirelli tyres, Runway tyres, Sumitomo tyres, and Toyo tyres.

But we don't just stop at helping you choose the right tyres – we also share tips on how to keep them in tip-top shape. From checking your tread depth and keeping your tyres properly inflated to extending their life through regular rotation and balancing, our articles have got you covered.

So, whether you're a car enthusiast or just looking to keep your vehicle safe and reliable, our car help and advice articles are here to help you make informed decisions about your tyres. Check them out and feel confident in your tyre choices!

Talk to Protyre

If you have any questions about the air pressure within your car's tyres, or if you would rather have your tyres looked at by one of our technicians instead of using an air compressor either at home or at a petrol station, contact your local Protyre centre today. We offer free tyre check appointments in all of our centres, during which our qualified and experienced tyre technicians will check for any signs of tyre wear or damage, as well as checking your tread depth and air pressure.

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About the author

Article Author Photo
By David Sholicar
David is the National Retail Operations Manager for Protyre. One of David’s areas of responsibility and expertise is dealing with the DVSA and MOT’s for Protyre. As the Authorised Examiner Designate Manager ( AEDM ) David deals with applications for changes to the many Vehicle Testing Stations ( VTS’s) including managing the growth of the Number of MOT testing stations that Protyre operate, allocating MOT tester roles, and monitoring the MOT Test logs to ensure that Protyre MOT standards are maintained as the best in the industry.
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