What is TPMS?

The air pressure within your tyres is the most important factor in determining how well they perform.

Pressure affects the tyre's speed capability, load carrying capacity, handling response, wear rate and overall safety. What is more, under-inflated tyres will cause your car to use more fuel and emit more CO2 emissions.

It's therefore critical for your safety and comfort that your tyres are properly inflated in line with the vehicle manufacturers' recommendations. Tyre pressures should be manually checked when they are cold at least once a month or before a long journey.

Click here for more benfits of maintaining correct tyre pressures

However, in order to assist you in monitoring the pressure in your tyres, all new cars are now equipped with a tyre pressure monitoring system (TPMS) which notifies you of any tyre pressure issues.
To discover how your TPMS works and how you need to look after it, take a look at Tyresafe.org's animation below. 


TPMS stands for Tyre Pressure Monitoring System

It's a system fitted to a vehicle which constantly monitors the pressures or pressure imbalance in the tyres and provides a warning to the driver if these fall below a certain threshold.
Such is the importance of correct tyre inflation, TPMS is a very useful safety feature. However, TPMS should not be seen as a replacement for regular manual tyre safety checks.

There are two types of TPMS systems fitted on cars today.

  • Direct systems use radio sensors are mounted inside each wheel to measure the tyre inflation pressures.
  • Indirect systems utilise the vehicle's existing Anti-lock Braking System (ABS)  sensors to measure and compare the rotational speeds of the tyres, which are affected by their pressures. For example; a tyre that is of a lower pressure to all the other tyres will rotate faster (when driving in a straight line) because the rolling circumference of the tyre is smaller.

Both system types work with the vehicle's main Electronic Control Unit (ECU) to alert the driver via dashboard warning lights to any pressure loss or variance issues.

TPMS & runflat tyres
Runflat tyres (RoF) are designed to provide a limited run-on period following a puncture. These types of tyres can be identified by the "RF" marking found on the tyre sidewall. Runflat tyres are only designed to run for a limited period, at a maximum speed of 50 mph with a limited load carrying capacity. Due to the nature of runflat tyres, these should only ever be fitted to vehicles equipped with TPMS.

You can see the identifying marks on runflat tyres by visiting our page which explains which runflat tyres can be repaired.

TPMS Law
Since November 2014, all new passenger vehicles sold in the EU must be equipped with TPMS. Furthermore, with effect from 1st January 2015, all vehicles fitted with TPMS will need to have a fully functioning system when undergoing their annual MOT test. Inoperative or faulty TPMS systems will result in an MOT failure.

Faulty TPMS equals a failed MOT 

Tyre Pressure and Your Safety
The air pressure within your tyres is the most important factor in determining how well they perform. Pressure affects the tyre's speed capability, load carrying capacity, handling response, wear rate and overall safety. What's more, under-inflated tyres will cause your car to use more fuel and emit more CO2 emissions.

It's therefore critical for your safety and comfort that your tyres are properly inflated in line with the vehicle manufacturers' recommendations. Tyre pressures should be manually checked when they are cold at least once a month or before a long journey. For more details on how to check your tyre pressures, visit any of our centres for assistance or take advantage of our Free Safety Inspections.

TPMS warning lights
TPMS warning lightIf the TPMS warning light on your dashboard illuminates, it should not be ignored as there may be a problem with the pressure in one or more of your tyres. At the earliest opportunity, find a safe place to stop your vehicle where you can manually check your tyre pressures against the vehicle manufacturer's recommended settings. These details can be found in your vehicle handbook, inside the fuel filler flap or on a placard located on the driver's door sill.

If you are unable to check your pressures yourself, either call for roadside assistance or locate your nearest tyre professional who will be able to help you.

Bush Tyres Branch Finder

Manual Checks
While the benefits of TPMS are widely recognised, it is important that they are not seen as a replacement for regular manual tyre safety checks. Pressures should be tested at least once a month or before any long journey, when the tyres are cold using an accurate and reliable pressure gauge. When checking pressures, it is advisable to also give the rest of the tyre a thorough visual inspection as well as ensuring the tread is not excessively or unevenly worn.

TPMS Servicing
To ensure your TPMS system continues to operate properly and reduce the likelihood of an MOT failure, it may be necessary to have the system serviced occasionally. TPMS sensors are designed to last for many years and miles, however, after a certain period, the sensor's internal battery will run out meaning a replacement is needed.

TPMS Valve Sensor | Bush TyresIn addition, sensors can become faulty or fail completely as a result of weather damage, corrosion or accidental damage caused when changing tyres. To ensure the sensor remains in good condition, many manufacturers recommend replacement of the valve cap and core components every time a tyre is changed.
When replacement TPMS sensors are fitted to your vehicle, your tyre fitter may need to programme the new component to the car using specialist diagnostic equipment.

Our centres have the testing equipment required to service & replace TPMS valve sensors. We have found one of the main reasons for prematurely replacing TPMS valves sensors is the use of metal or aftermarket valve caps, whereby, when trying to remove the valve cap the valve stem snaps because the cap has corroded itself onto the valve stem. It is recomended to only fit plastic or alloy valve caps. If this happens to you it's not always a case of replacing the whole sensor, though we can if required. We are able valve sensor service kits to replace just the valve stem & seals in many cases.

If your TPMS sensor develops a fault, under no circumstances should the sensor be removed and replaced with a ‘standard' non-TPMS type valve. Removing the sensor will not only reduce your safety on the road, it will also result in your car failing the MOT.

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