Maintaining proper tire pressure is essential for the safety and performance of a vehicle. It also plays a significant role in decreasing fuel consumption and extending tire life.
All tires lose inflation over time and, as many modern vehicles have extended service intervals, tires can become dangerously under-inflated without regular checking by the vehicle driver.
In addition to increased fuel consumption and tire wear, long periods of driving with low tire pressures can cause additional stress on the tire sidewalls. This results in increased operating temperatures that can lead to premature tire failure.
Tires operating with low pressures can also affect the vehicle's handling and performance. In a worst-case scenario, under-inflation can lead to a tire blowout or tread separation.
Automated Tire Pressure Monitoring Systems or TPMS provide a means of reliable and continuous monitoring of the vehicle tire pressure and are designed to increase safety, decrease fuel consumption and improve vehicle performance.
There are two types of tire pressure monitoring; direct and indirect.
The direct monitoring system uses a pressure sensor mounted inside each wheel and uses a wireless transmitter to give direct tire pressure readings.
The indirect system uses the vehicles wheel speed sensors to determine if a tire is underinflated when compared to each of the other tires.
TPMS can be fitted to all vehicle types using conventional and run-flat tires.
With a Tire Pressure Monitoring System installed on a vehicle, drivers can monitor the tire pressures and temperatures from the driver's seat to ensure that their tires are properly inflated under all operating conditions. The systems are also designed to ignore normal pressure variations caused by changes in ambient temperature.
The sensor installed inside each wheel is able to respond to as little as a 3PSI or 20Kpa drop in pressure. Real-time information is sent via wireless signal to a display in the vehicle. If a fluctuation occurs, an audible and visual warning instantly alerts the driver allowing time for the vehicle to be stopped or driven to a service station for tire repair or re-inflation. The tire is used to enclose the unit as protection from the outside environment. An on-board computer receives the radio messages from the sensors, which are coded for individual wheel identification.
The interactive display inside the vehicle shows:
The driver can use the display control buttons to check the status of each tire.
In OEM installations, each time the ignition is switched on, an indicator on the instrument panel and on a system display provides information about all four tire pressures, and gives a "Pressure OK" message if all is well. An indicator on the display will “flash” whenever pressure loss is detected. In the case of minor deflation, an orange "Service" light is shown, and indicates the faulty tire. If the pressure is dangerously low, a red "Stop" light flashes, accompanied by a punctured tire icon, indicating that an immediate wheel change is needed.
The sensors are activated by a centrifugal switch and transmit only when the vehicle is in motion. When the vehicle stops the sensors return to sleep mode to extend battery life, however the driver is still able to review the latest signals received from the wheels before the vehicle was stopped.