How can I check my tyre pressures?

We show you how to find the correct tyre pressures for your car, how to check your tyre pressures and show you our tyre inflator picks

Almost as important as the tyres themselves, correct tyre pressures save fuel, give you maximum grip and keep you safe. Here’s how to check yours.

It might be just one of those dull tasks on your to-do list that you never get around to, but the reality is that keeping your tyre pressures at the correct level is an all-round win. Tyres set to incorrect or uneven pressures wear out more quickly, use more fuel, don’t offer as much grip and braking performance and are more likely to fail or blow-out - which should be more than enough reasons to keep them checked.

How do I check my tyre pressures?

1. Make sure you know the correct tyre pressures for your car before starting (details of how to find this data are below).

2. To accurately measure the current pressure in your tyres you can use a handheld pressure gauge, a portable tyre inflator or an inflator at a fuel station or garage. 

3. As tyre pressures rise slightly when the tyres are warm it is best to check them before a journey if possible.

4. Remove the dust cap from the tyre valve and push the connector firmly on - this should then give you a reading on the measuring device.

5. If you’re using an automatic device you simply set the tyre to the desired pressure and it will inflate until the correct reading has been achieved - and don’t forget to replace the dustcaps afterwards.

Converting Tyre Pressure In BAR to PSI

Tyre pressures are almost always expressed as PSI (then BAR). However, some compressors and inflators are in BAR. The chart below converts pressure in BAR to PSI.

BAR PSI BAR PSI BAR PSI BAR PSI BAR PSI
1.30 bar 17 psi 1.90 bar 27 psi 2.60 bar 37 psi 3.25 bar 47 psi 3.95 bar 57 psi
1.35 bar 18 psi 1.95 bar 28 psi 2.65 bar 38 psi 3.30 bar 48 psi 4.00 bar 58 psi
1.40 bar 19 psi 2.00 bar 29 psi 2.70 bar 39 psi 3.40 bar 49 psi 4.10 bar 59 psi
1.45 bar 20 psi 2.10 bar 30 psi 2.75 bar 40 psi 3.50 bar 50 psi 4.15 bar 60 psi
1.50 bar 21 psi 2.15 bar 31 psi 2.80 bar 41 psi 3.55 bar 51 psi 4.50 bar 65 psi
1.55 bar 22 psi 2.20 bar 32 psi 2.90 bar 42 psi 3.60 bar 52 psi 4.80 bar 70 psi
1.60 bar 23 psi 2.25 bar 33 psi 3.00 bar 43 psi 3.70 bar 53 psi 5.20 bar 75 psi
1.70 bar 24 psi 2.30 bar 34 psi 3.05 bar 44 psi 3.75 bar 54 psi 5.50 bar 80 psi
1.75 bar 25 psi 2.40 bar 35 psi 3.10 bar 45 psi 3.80 bar 55 psi 5.85 bar 85 psi
1.80 bar 26 psi 2.50 bar 36 psi 3.20 bar 46 psi 3.90 bar 56 psi 6.20 bar 90 psi

What are my tyre pressures?

There’s no point in checking tyre pressures if you don’t have the right information in the first place, so it is worth taking the time to check. Start by checking the labelling on the side of your tyres; the letters and numbers give the tyre dimensions. It’s important to start here because one model of car can wear several different tyre sizes, so make a careful note of the information which should look something like this: 195/65 R15 91H.

The tyre pressure information for your specific car may be displayed in a number of places; on the B-pillar of the driver’s door or inside the fuel filler flap are the most common locations but the information will also be repeated in the handbook. Pressures for all the tyre sizes available for your car will be displayed, so check this against the specific information you noted down earlier. Many manufacturers also provide a set of different pressures depending on the vehicle load; all of these pressures will be safe for your car to use but it is best to choose the recommended levels, and don’t be tempted to mix pressure levels front to rear - this could upset the balance of your car considerably.

If you can’t find the relevant information in your vehicle you can search out the correct pressure via the manufacturer’s website or one of a number of independent websites such as www.tyre-pressures.comhttps://www.tyresafe.org/check-your-pressures/ and https://www.oponeo.co.uk/advice-and-tips/tyre-pressure. If your vehicle is fitted with aftermarket wheels and tyres that don’t match the original specification you should contact the tyre manufacturer for recommended pressures.

What are tyre pressures measured in?

The most common tyre pressure measurements are the imperial PSI (pounds per square inch) or the metric Bar, although some vehicles including some Mercedes-Benz models will display them in kPa (kilopascal) which is also a metric unit. If you need to convert between them, 15PSI is equivalent to 1 bar and 103kPa.

What tyre inflators would you recommend?

Ring RAC620 12V Analogue Tyre Inflator

A favourite tyre inflator here at Honest John, the Ring RAC620 keeps things nice, simple and effective. Another plug-and-play device, the Ring RAC620 takes a 12V feed to power the compressor with an analogue dial displaying in PSI, BAR and kg/cm2. Also included is an LED light with red and white flashing modes to attract attention in case of emergency with an adaptor set to inflate toys and bikes. For a few pounds more you can have the RAC600 version with a digital readout too.

Mbuynow Tyre Inflator

Covering all the bases at a reasonable price, the Mbuynow Tyre Inflator is ready for just about anything. One of the more compact offerings available via Amazon, it still offers a 3-metre power cable into your 12V socket and has enough power to dish out 27 litres a minute up to 100PSI of pressure. The backlit digital display means accurate pressures are easy to achieve and a trio of adaptors gives you the option to blow up a variety of inflatables.

 

Scheppach Air Case 2LTR Portable Air Compressor

A compressor to tackle a huge variety of jobs, this device from Scheppach is packed with accessories. The 1.5hp electrical motor pushes out a massive 180 litres of air per minute to make short work of any task, while the 12-piece air tool kit includes a variety of fittings. This model is also equipped with a tank to enable continuous use up to 116PSI, all contained within its own case for easy transportation.

 

See all of our tyre inflator best buys

Ask HJ

What is the maximum I can inflate my tyres to stop them flatting when in storage over the winter?

My Mazda MX-5 is covered for the winter and wired to my battery charger, so I cannot move it. The tyres are Bridgestone Portenza 205-45R17 84W CKC4509. What is the safest maximum I can inflate them to lessen tyre flatting?
The maximum cold tyre pressure should be printed on the sidewall. If you're storing for more than a month, we'd recommend disconnecting it from the battery charger and rolling the tyres. If you really can't do that, there are some anti-flat spot cradle gadgets you can buy - although we've got no experience of using them. If you do decide to over inflate don't forget to let the extra air out.
Answered by Keith Moody
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