How do tyre pressure sensors work?

3rd October 2019


Many modern vehicles are fitted with tyre pressure monitors these days. But how do tyre pressure sensors work? And how accurate are they? Find out all you need to know today from our helpful guide.

Why is tyre pressure important?

Firstly, it's important to understand why having correct tyre pressure in your tyres is so important. If your car is operating on tyres with low levels of air, this can be extremely dangerous not only for you as a driver, but for other drivers on the road too. Under-inflated tyres can increase braking distances, decrease control of handling and provide extra drag which will reduce fuel efficiency.

A partially inflated tyre also becomes hotter quicker - meaning the tyre will naturally wear down faster, and can cause issues for both your driving and your tyres.

However, if your vehicle is running on tyres with over-inflated tyres, or too much air, this can be detrimental to performance, too. As tyres will have less surface contact with the road when over-inflated, braking, handling and tyre wear will naturally suffer.

What is a tyre pressure monitoring system?

A tyre pressure monitoring system (TPMS) is an electronic system fitted in your vehicle which monitors air pressure in your tyre. This system alerts you if your tyre pressure is dangerously low. There are two main types of TPMS:

  • Direct TPMS - this employs sensors that are mounted within the tyre which monitor the pressure levels. If the pressure drops to a pre-set level, this flags up as a warning on the car's dashboards.
  • Indirect TPMS - this uses the anti-lock braking system (ABS) wheel speed sensors to detect wheels which may be rotating at different speeds. This would suggest that under-inflated tyres' rolling radius may be slightly lower, meaning you should check your tyre pressure.

Indirect TPMS is a much simpler system, but is less accurate than direct TPMS - which can determine accurate readings from all four wheels, allowing you to monitor your tyre pressures precisely.

If your vehicle warning light appears on your dashboard, you will need to check your vehicle's air pressure in your tyres, and inflate any that are too low. Once you have rectified the low-pressure issue in the tyres, the warning light should disappear.

How to check your vehicle's tyre pressure

There are various ways to check your tyre pressure. These include:

  • The air machine at a petrol station
  • Digital tyre inflator
  • Tyre pressure gauge

To check your tyre pressure, the process is always the same. Remove the valve cap - you'll find this screw cap near the rim of the wheel. Push the gauge onto the valve and you will receive a reading. Ensure the gauge is tightly fitted onto the valve for an accurate reading.

You will then be able to pump air into your tyres using air machines at a petrol station which, when pre-set to the manufacturer's specifications on tyre pressure, will stop when the tyre is optimally inflated. To find out your tyres' recommended tyre pressure, refer to your vehicle handbook, or they can sometimes be located on the side of the driver's car door.

However, if you are persistently receiving warnings from your TPMS that your tyres are dangerously low in pressure, it could be the sign of a slow puncture. If this is the case, don't keep inflating your tyre with air when the tyre pressure monitor comes on - you may instead need to replace your tyre with new car tyres. But before that - find your local Tyre Group centre today and receive a diagnosis, as your tyres may be repairable.

Now you know more about tyre pressure indicators and how they work, learn more about tyres, motoring advice and more from our news section. Alternatively, locate your local Tyre Group centre today to check your tyre pressure in one of our garages today.

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