Tyre Pressure Monitoring Systems (TPMS)

If one of these symbols is flashing on your dashboard display

Or has this happened to your tyre pressure monitoring systems valve

etyres can fix this for you at home or work

Tyre Pressure Monitoring Systems are fitted to cars to monitor the air pressure within the tyres and to warn the driver if they drop below the recommended levels. If the pressure drops more than 20% below the manufacturers recommended pressure then the system alerts the driver by and visual and/or audible warning inside the car.
Most tyre blow outs are caused by driving on under inflated tyres and a TPMS system increases your safety by reducing the chance of these incidents. Driving with under-inflated tyres also uses more fuel and tyre wear so having a TPMS system also saves you money on fuel and increases tyre life.
All new vehicles sold in the EU now must have a form of TPMS fitted to them by law.

Most TPMS systems use a tyre pressure sensor which is attached to the back of the tyre valve. Until recently motorists had to return to their main dealer to buy a replacement tyre pressure sensor valve, have it fitted and then programed to work with the car. The main dealers can be very expensive for this. Now etyres can supply a replacement tyre pressure sensor valve for much less than the main dealer. All our TPMS sensor prices are fully inclusive of fitting, programing and VAT and we will even come to you at your home or work to do the job so you do not have to waste time dropping off and collecting your car from the main dealer.

TPMS valve service kits

In order to prolong the life of your TPMS valves we recommend having your TPMS valves serviced each time you change your tyres. For a small additional fee we will replace the important components of your sensor such as the valve core, rubber grommet, valve retaining nut and dust cap to ensure that they continue to give an air-tight seal. Valve service kits are available from £6.90.

History of TPMS

Tyre Pressure Monitoring Systems were first designed after Ford Explorer vehicles in the USA were involved in a series of fatal accidents due to the drivers running with tyre pressures that were too low. The U.S. Government then introduced legislation to ensure all cars had tyre pressure sensors fitted to the wheels.
In Europe only a few vehicles have had tyre pressure sensors until recently. Early adopters of the technology were Renault, Citroen and Peugeot and cars such as the Renault Laguna have had tyre pressure sensors fitted since around 2003. New EU legislation means all new cars in the EU must have some form of TPMS fitted.

Benefit of TPMS

The primary function of TPMS is safety. Up to 75% of tyre related accidents are caused by under-inflation. Tyres are naturally porous and leak air slowly. All motorists are advised to check their tyre pressures at regular intervals because of this. The reality is that most motorists do not check their tyre often enough and so TPMS helps to keep them safe.
Another big advantage of TPMS is that correctly inflated tyres use less fuel and reduce premature tyre wear. This has a big saving in carbon emissions and a cash saving for the motorist’s pocket.

Tyre pressure monitoring systems facts

• 75% of tyre blow outs are caused by under inflation
• A tyre can be up to 50% under inflated before appearing as such. (tyres naturally lose 0.2 bar pressure per month)
• Today in the UK at least 50% of cars have one tyre dangerously under inflated
• 41% of major accidents in Germany are linked with a tyre problem
• 9% of fatal accidents on French motorways are linked to tyre under inflation

Direct TPMS or Indirect TPMS

There are two types of tyre pressure monitoring systems. Direct and Indirect.

Indirect TPMS

How does indirect TPMS work?

Indirect TPMS uses the ABS wheel speed sensor of the vehicle to monitor the rotation speed of the individual wheels. If a deflation of a tyre occurs the resulting decrease in tyre circumference and increase in wheel speed triggers the TPMS and advises the driver accordingly. Indirect TPMS is currently far more common than the direct sensor based alternative. However this is changing rapidly as almost all manufacturers are now adopting the direct TPMS approach on their newer vehicles.

What are the advantages of indirect TPMS?

The advantages of the ABS based system include the fact that the system uses technology and equipment that is already fitted to the vehicle. There are also no sensors fitted inside the wheel/tyre assembly which makes the tyre fitting process easier than the sensor based systems. However, as indirect TPMS measure wheel speed rather than actual tyre pressure, it can be inaccurate and also not as sensitive to a change in pressure as direct TPMS. It also requires the vehicle to be driven before it can detect a fault which can mean driving with a flat or even dangerous tyre for a period of time before you are made aware of the puncture. Also if all four wheels are equally deflated it they will all rotate at the same speed and so it will not pick up an issue.

Direct TPMS

How does direct TPMS work?

Direct or sensor based TPMS has a pressure monitoring sensor fixed inside the wheel and tyre assembly. This is usually attached to the back of the valve and constantly monitors the internal pressure and temperature of the air inside tyre. This information is relayed to a receiving unit on the vehicle body which is connected to a processing unit in the electronics system of the vehicle. This alerts the driver to a loss in tyre pressure.

What are the advantages of direct TPMS?

The advantages of direct TPMS include accurate monitoring of the actual pressure inside the tyre and an immediate warning of a tyre deflation without needing to drive the car before a warning flags up. By alerting you to a problem with your tyres quickly it can prevent unnecessary damage to the tyre sidewalls. However, it a more complex system than indirect TPMS and it can be more difficult to fit the tyre due to the possibility of damage to the sensor if extra care is not taken. etyres are experts in direct TPMS sensor valve replacement as explained at the top of this page.

Why do sensors need to be replaced

The sensors have batteries with a lifespan of 5-7 years or 100,000 miles. The batteries are not replaceable and so when your battery fails you need to have a new sensor fitted. When the sensors detects a low pressure it transmits more often so a car that has been driven for a long period of time on low tyre may need the sensor replacing sooner.
The valves on sensor are also prone to corrosion if left un-serviced and this can also require a replacement sensor valve in some cases. A major cause of sensor failure is corrosion to the valve stem caused by use of a brass valve core inside an aluminium stem. This causes galvanic corrosion and is a major killer of TPMS valves. etyres only fit nickel plated valve cores to prevent this from happening. For a small addition cost etyres will fit a TPMS service kit to prolong the life of your TPMS sensors.

Cars registered after 1st January 2012 must have this TPMS system functioning to pass the MOT test.