What Is TPMS ?
A tyre pressure monitoring system or TPMS is an electronic system for monitoring the air pressure in a vehicle tyre and automatically transmitting a warning to the driver in the event of an under and, in some cases, over inflated tyre. These systems have been legislated to be progressively installed on all new passenger carrying US and EU vehicles and similar legislation is being introduced worldwide.
The majority of systems use direct tyre sensors which transmit real time tyre pressure information to the driver of the vehicle either via a dashboard display or a warning light referred to as the tread light. The sensors are physical pressure transducers which are attached to the back of the valve stem or are in a form which is banded to the wheel.
The Tyre Pressure Monitoring System sensors also transmit data such as their unique sensor ID, temperature, pressure, battery life (where applicable) and other diagnostic information. This data is sent to the Engine Control Unit (ECU) or specific receiver on the vehicle. Those vehicles which have graphical displays of the sensor positions can then show on which wheel there is a problem.
Why There's Need For TPMS
Tyre Pressure Monitoring helps drivers to properly maintain their vehicle tyres, improves vehicle safety and aid fuel efficiency. The National Highway Traffic Safety Administration (NHTSA) in the US has estimated that 533 fatalities per annum are caused by tyre defects in road accidents. The EU has carried out a similar review. Adding TPMS to all vehicles could avoid 120 of the 533 yearly victims and save as many as 8,400 injuries every year. Sécurité Routière (the French Institution for Road Safety) estimates that 9% of all fatal road accidents are attributable to tyre under-inflation and the German DEKRA estimated that 41% of accidents with physical injuries are linked to tyre problems.
Tyres leak air naturally and over a year a typical new tyre can lose between 3 and 9 psi. As most drivers only check their tyres at service intervals and when problems occur there is significant scope for fuel savings and efficiencies using a Tyre Pressure Monitoring System.
Given this background the US Federal government has legislated for the mandatory use of a Tyre Pressure Monitoring System. The TPMS mandated by the US law must warn the driver when a tyre is under-inflated by as much as 25%. There is a similar legislation for the EU, which has been passed in two steps. Since November 2012 all new registered vehicle models have to have TPMS installed. From November 2014 this will apply for all new registered vehicles.
The facts are that underinflated tyres are not just a huge safety issue. The other major benefits of properly inflated tyres include better fuel economy, longer tyre life and better stopping performance. The reality is that properly inflated tyres monitored by a properly running Tyre Pressure Monitoring System will save the consumer money.
You can't tell from it's outside even it's pressure is 50% less
70 % inflated tyre
100 % inflated tyre