Checking tyre pressure

It's important to maintain the correct tyre pressure for your vehicle. Ensuring your tyres are inflated to the recommended pressure can help you stay safer on the road, as well as saving money on replacement tyres and fuel consumption.

Why is the correct tyre pressure important? Maintaining the correct pressures for your vehicle is important because it can help to...

Reduce the risk of potential blow-outs

The air pressure inside a tyre is what helps to bear the vehicle's weight. If a tyre is under-inflated there may not be enough air to properly support the vehicle. This can put extra pressure on the tyre's sidewalls, causing them to flex beyond their normal limits. This in turn can lead to a build-up of excessive heat and a potential high speed blow-out.

Improve road handling

An under-inflated tyre will be less rigid than it is supposed to be, resulting in poorer handling and steering control. An over-inflated tyre reduces the surface area of the tyre that is in contact with the road at any one time. This can lead to a loss of grip and increased braking distance, especially in wet or icy weather conditions.

Increase tyre lifetime

A correctly inflated tyre is designed to spread the wear and the pressures that are exerted on its surfaces. An over-inflated tyre can cause premature wear along the centre. Over-inflated tyres can also be more susceptible to damage caused by driving over potholes and other irregularities on the road.

An under-inflated tyre can cause premature wear to the tread and to the shoulder of the tyre – the part at the edge of the tread where it changes to the sidewall.  By law, car tyre treads in the UK must have a minimum depth of 1.6mm and the tyre must also have intact shoulders and sidewalls. Driving with tyres at the recommended pressure can save money by increasing the safe and legal lifetime of the tyres.

Provide more efficient fuel consumption

Under-inflated tyres are less rigid and more of the surface area of the tyre will be in contact with the road at any one time. This results in greater friction between the tyre and the road, requiring more power to move the car.

This, in turn, means you will use more fuel. Ensuring your tyres are inflated to the correct pressure will help save you money in fuel costs and will also help the environment by lowering your general Co2 emissions.

Finding the recommended pressure

There are a number of ways to find the correct tyre pressure. Car manufacturers specify the recommended pressures for tyres fitted to their vehicles. These recommended pressures can be found in the car owner's manual. They may also be printed on the inside of the driver's door or the inside of the petrol tank cap.

The air compressors available to customers at many petrol stations will often have a chart, listing recommended tyre pressures for many popular makes and models of cars.

There are also a number of websites that allow you to check your recommended tyre pressures online. You can generally do this by entering the make, model and year of your car. Some sites will also allow you to enter your registration number and will find your car specifications for you.

Front and rear tyres may have different recommended pressures. Recommended pressures may also vary depending on the load which the car is carrying. If you are carrying a heavy load or towing an additional load such as a trailer or caravan, you should check if your tyres require extra inflation.

Checking the actual pressure

You should only check tyre pressures when the tyres are cold (i.e. before making a journey of any great length). Driving causes the tyres to heat up and this can lead to inaccurate pressure readings. Making a short journey to check your tyres at a nearby petrol station might not make a huge difference, but to ensure the most accurate reading you should allow the tyres time to cool down before taking a reading.

You can check your tyre pressures using a tyre pressure gauge. You can buy pressure gauges to use at home or on the road or at a garage or petrol station with an air compressor.

Remove the tyre valve cap, attach the pressure gauge and check the reading. This may be a digital reading, an arrow on a gauge or a 'pop out' stick with measurements depending on the type of gauge you are using. Tyre pressure can be expressed as either bar pressure or psi pressure.

If you are checking a particular tyre because you think it looks or feels under-inflated, it's generally worth checking all your tyres at the same time. Spare tyres should also be checked at regular intervals.

If you are not confident in checking the pressures yourself, most garages will also do it for you.

Inflating your tyres

Tyres can be inflated using compressors and pumps of various types. Some will have a built-in pressure gauge, allowing you to set the desired pressure or keep an eye on the gauge until you reach the correct pressure. Air can be let out of an over-inflated tyre by partially removing the gauge or compressor nozzle from the tyre valve until you hear the hissing of escaping air.

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