As part of Tyre Safety month, we continue our look at key parts of tyre maintenance. One of the key aspects of this, is tyre air pressure.
Let’s start simple. Your
tyres need air - not too much, not too little. A specific recommended pressure level, advised by the vehicle manufacturer. Meaning the required pressure will vary by different cars, makes, models, and trims.
Most vehicle manufacturers display the correct tyre pressure figures on a sticker on the inside of the driver’s door. If it’s not there, check your car’s handbook.
For safety, check your pressures once a month and before a long journey.
Some cars have different recommendations for the front and back, so make sure to check both.
Tyre Pressure: Why It Matters
Tyre pressure is one of those unseen things that helps to make other parts of a car work better.
If the pressure is too low, you’ll likely end up using more fuel. At the same time your steering goes heavy, and your tyres wear faster at the edges.
For a tyre that is too high in pressure levels, the car will start to feel jittery. Braking responsiveness will worsen, and you’ll wear out the middle of the tread first.
The wrong pressure can increase your stopping distance by several metres.
That’s the kind of thing you only realise when it’s too late.
Find out more about
tyre wear patterns and what they can tell you about tyre pressure.
What Tyre Pressure Really Means
Pressure is just the amount of air pushing out from inside the tyre. It’s typically measured in:
- PSI – the imperial unit you’ll see most often.
- BAR – metric, used across Europe.
- kPa – rarely used outside of manuals.
BAR - PSI - kPa Conversion Table
| BAR
| PSI
| kPa
|
|---|
| 1.40
| 20
| 140
|
| 1.50
| 22
| 150
|
| 1.60
| 23
| 160
|
| 1.70
| 25
| 170
|
| 1.80
| 26
| 180
|
| 1.90
| 28
| 190
|
| 2.00
| 29
| 200
|
| 2.10
| 30
| 210
|
| 2.20
| 32
| 220
|
| 2.30
| 33
| 230
|
| 2.40
| 35
| 240
|
| 2.50
| 36
| 250
|
| 2.60
| 38
| 260
|
| 2.70
| 39
| 270
|
| 2.80
| 41
| 280
|
| 2.90
| 42
| 290
|
| 3.00
| 44
| 300
|
| 3.10
| 45
| 310
|
| 3.20
| 46
| 320
|
| 3.30
| 48
| 330
|
| 3.40
| 49
| 340
|
1 BAR equals roughly 14.5 PSI.
How to Find the Correct Tyre Pressure
As we touched upon previously, the recommended tyre pressure for your car is often hiding in plain sight:
- Sticker or plate: open the driver’s door and look at the frame. Sometimes it’s inside the fuel flap.
- Owner’s handbook: usually repeats the same numbers and includes “laden” vs “unladen” variations.
How to Check and Adjust Tyre Pressure
Maintaining the tyre pressure is thanfully not a difficult task. And one that most drivers will feel comfortable tackling – be it at home or at a petrol station.
Here are the required steps to check and/or adjust the tyre pressure of your tyres.
- Wait until tyres are cold. If you’ve just driven recently, give it some time before you take a reading. Warm tyres expand and so the reading will not be accurate.
- Park safely. Try to make sure you are on a level surface. Turn off the engine and ensure that the handbrake is on.
- Remove the valve cap. Once you have taken off the valve cap, be aware that they can easily roll away or become lost if you are not paying attention. I speak from personal experience on that front. Maybe pocket it to keep it safe whilst you carry out the rest of the steps. Sometimes I think the hardest part of tyre maintenance is not losing the valve caps. Seriously.
- Press the gauge firmly. Take your tyre pressure gauge, hold it straight and press firmly into the valve. You will often be required to screw the gauge onto the valve to ensure a strong connection. Listen for a faint hiss - that’s normal.
- Read the number. The gauge will give you a reading of the current air pressure within the tyres. Compare it with your sticker. If you’re off by more than 2 PSI, fix it.
- Inflate or deflate as needed. It’s best to add air in short bursts, checking the pressure as you go. If there is too much pressure, or you add too much, you can let air out by pressing the valve pin gently.
- Re-check and replace the cap. Once you have hit the correct air pressure, remove the gauge and screw the valve cap back on.
Remember to reset the tyre pressure on the car’s onboard computer. To ensure that the TPMS does not flag pressure level decreases incorrectly.
If you have a spare wheel in your boot, make sure to check and maintain the air pressure of this tyre too.
Tyre Pressure Maintenance Tips
Tyre Pressure for Electric Vehicles
As EVs are generally heavier than cars with an internal combustion engine, the extra weight means higher pressures. Sometimes this can be as much as several PSI more than a petrol model. Also, range suffers fast when underinflated.
This is why it is important to make sure to check the recommendations for your specific model and/or trim.
Heavy Loads or Towing
You’ll often find “laden” pressures listed next to the normal ones. They matter. As the extra weight in your car when it is full or passengers and luggage will affect the tyres. Make sure to use the correct laden recommendations when applicable and then drop back down afterwards.
TPMS (Tyre Pressure Monitoring System)
It’s clever but not perfect. Direct systems show real readings. Indirect ones just notice something’s different. If the light pops up and you’ve checked the tyres, you might need to reset it.
How Often Should You Check?
Ideally? Once a month. Or before any long drive.
A good tip is to add a reminder to your phone. Or just make it a ritual at a certain time each month. Combine it with other tasks such as filling the screen wash fluid.
I tend to do it on the first Sunday of each month. No science there. Just habit.
Tyre Pressure Tools
- Digital gauge: easy to read and accurate.
- Portable inflator: 12V or rechargeable - great for home or travel.
- New valve caps: cheap, essential. Replace missing ones. Did I mention they get lost easily…?
- Tyre app or logbook: track readings to spot slow leaks early.
You don’t need all of them, but a decent gauge is worth its weight in fuel savings.
Tyre Pressure Check Recap
- Check when tyres are cold.
- Use a reliable gauge.
- Follow the sticker/manual.
- Adjust in small steps.
- Check the spare.
- Repeat monthly.
- Don’t ignore uneven wear or noises.
Five minutes of attention for thousands of miles of peace.
Written with help from practical experience, mild impatience, and a few lost valve caps.
