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Tyre Pressure - How to Check Yours

Once you’ve purchased a set of new tyres, you’ll want them to last, so it’s important to know how best to maintain them.

A key way to do this is to do a regular tyre pressure check. You can do this yourself using a tyre pressure gauge or any local National Tyres and Autocare branch will do this for you free of charge.

What is car tyre pressure and why is it important?

Tyre air pressure is measured in either pressure per square inch (PSI) or BAR pressure, which is the metric unit of atmospheric pressure equal to 14.50 pounds per square inch. Converting between bar pressure and PSI pressure is easily performed using this online conversion tool.

Keeping the tyre pressure close to the recommended pressure level helps to increase the amount of time the tyres are used, maintains fuel efficiency, and promotes better vehicle safety.

What is the correct tyre pressure for my vehicle?

First, you need to find the recommended pressures for the tyres. These can be found in several places:

Your vehicle’s handbook

Stamped into the sill of the driver’s side door

Inside the fuel cap

The recommended pressure is set by the vehicle manufacturer and varies from model to model.

Do be aware that there are different pressures for different vehicle loads – the more passengers or luggage, the higher the pressure will need to be.

Tyre Pressure Gauge

With a pressure gauge, you can check each tyre pressure individually.

Remove the valve cap and attach the pressure gauge to it. Verify what your vehicle’s pressure should be and insert the number into the gauge. More air can be added for free or a small charge at most petrol stations. If there is too much pressure in the tyres, removing the cap can let the air out to bring the value down to the correct tyre pressure. When you reach the correct tyre pressure, the device will sound to let you know. Simply replace the valve cap.

What happens if your car tyre pressure is incorrect?

When tyre air pressure falls below 60 percent, a tyre’s lifespan is reduced by over a third.

Accelerated wear

Initial indicators of an under-inflated tyre include accelerated wear on the exterior sides of the tyre. Given sufficient time, the tyres can wear down to the point where they’re no longer legal to use on the roads.

Tyre blow outs

When air pressure is too low, the sidewall of each tyre becomes compromised due to the tyre flexing further than recommended. This creates a higher internal temperature while the tyre is in use, considerably increasing the chance of a tyre blowout.

Fuel Efficiency

An under-inflated tyre reduces fuel efficiency. Friction is caused when driving and this is known as rolling resistance. Due to the increased friction caused by under-inflation, more fuel is needed to push the vehicle forward. This leads to high fuel consumption and greater CO2 emissions.

Equally, if tyre pressures are too high, these can cause the tyres to bounce as you drive and cause mass uneven wear across your tyres.

How can I avoid incorrect tyre pressure?

Check tyre pressures frequently to ensure that tyres last longer and less fuel will be used.

Run Flat Tyres

Run flat tyres can be used even if they deflate. Even with reduced air pressure, run flat tyres are capable of 50 miles at 29mph or slower, before needing to be replaced. Reinforced tyre sidewalls with rubber inserts provide added support for the vehicle’s weight.

Tyre pressure monitoring systems (TPMS) are required when using run flat tyres because tyre pressure levels cannot be confirmed. This also applies to vehicles being towed by a car with run flat tyres.

Tyre Pressure Monitoring Systems

From November 2012, EU regulations legislated that all new vehicles in Europe come with a TPMS system.

This warning system is capable of prompting the driver when a tyre is too hot, or the air pressure is incorrect, within seconds.

This new system avoids the need to check tyre pressures regularly, almost eliminates unnecessary wear on the tyres, improves fuel efficiency, cuts C02 emissions and dramatically cuts the likelihood of a tyre blowout.

Five top tips for taking care of your tyres

Check the tyre pressures on all tyres (including the spare) every three weeks, before going on holiday, and if carrying more people or more luggage suggesting that the tyre pressure needs to be boosted. Check pressures when tyres are cold. Look up the correct tyre pressure in the driver’s handbook, door sill or petrol filler cap. When towing, check the pressure levels of the second vehicle too. When checking tyre pressures, look at the condition of the tyres for cuts, tears, tread wear, and other warning signs of future problems.

Happy to help

If you need any further advice on air pressure or simply need help to find cheap tyres fitted by technicians, you’ve come to the right place. Contact us today and we’ll help you find the best match of tyre for your vehicle.