You have no doubt noticed that your tyres deflate slightly with use. This is perfectly normal, tyres are not 100% airtight and naturally let out some air which is why you need to check the pressure regularly. Maintaining the correct pressure for your tyres is not only vital for your safety, it also helps to prevent premature wearing of your tyres and improve their energy efficiency. In fact, most tyre damage is the result of incorrect pressure. Find out how to properly manage your tyre pressures, when and how much to inflate each tyre.
Incorrectly inflated tyres: what are the dangers?
Incorrect tyre pressure puts you at risk and costs you money due to:
- more rapid wear to your tyres
- longer braking distances
- diminished handling and driving precision
- increased risk of aquaplaning
- higher fuel consumption
In particular, if your tyres are over-inflated (excess pressure), they will be too rounded reducing their contact surface with the road. This means that your tyres will have less grip and less ability to absorb irregularities on the road surface. With overinflation, your tyres will wear more quickly towards the centre of the tyre.
Conversely, under-inflated tyres (insufficient pressure) will have an increased contact surface across the breadth of the tyre. This will lead to overheating and a possible blowout which could cause you to lose control of your vehicle. Even before the tyre blows, you will experience poorer vehicle handling, particularly on the wet, and increased fuel consumption.
What pressure for your tyres?
You can find the recommended tyre pressures for your vehicle in the handbook and/or on a label stuck on the inside of the driver's door or on the petrol cap.
The recommended tyre pressure is not necessarily the same for the front and rear tyres. It is important however to make sure that both tyres on the same axle are inflated to the same pressure.
In some cases you should slightly increase your tyre pressures:
- If you are towing a trailer or a caravan, increase the pressure of your rear tyres by 7 to 12 PSI (0.5 to 0.8 bars).
- In the winter, add 3 PSI (0.2 bars) to the recommended pressure in order to compensate for the reduction in pressure in the cold.
When should you check your tyre pressure?
Remember to check your tyre pressure at least once a month and before you go on any long journeys. You can do this at any petrol station with an air pressure gauge or at home if you have the right equipment (tyre pressure gauge, compressor or foot pump).
If you see any signs of abnormal wear on your tyres or detect any vibrations when driving it may be that your tyres are incorrectly inflated, in this case you should check the pressure more often.
Remember to check the pressure of your spare tyre!
How to correctly inflate your tyres
Tyre pressure should always be checked cold i.e. before you have driven 2 miles (at low speed) or at least 2 hours after driving the car. If you have to inflate warm tyres, add 4 PSI (0.3 bars) to the recommended pressure. Whatever you do, avoid measuring tyre pressure in direct sunlight or when your vehicle has been parked in hot weather.
To check the pressure, unscrew the cap covering the tyre valve, fit the nozzle of the pressure pump onto the valve and check the reading on the screen. You can then adjust tyre pressure using the + and - buttons.
Don't forget to put the valve caps back on properly to keep the tyres fully airtight.
If you check your tyres when warm, the pressure reading will likely be too high - this is normal, so never deflate your tyres in this case. Wait for the tyres to cool down and check again.