There are two types of tyre pressure monitoring systems: direct and indirect systems. Both kinds of systems are designed to inform the driver of low tyre pressure, which increases safety and saves fuel.
Here are the key differences:
Direct tyre pressure monitoring systems:
- Sensors directly on the tyres: In direct air compression systems, the sensors are attached directly to the tyre valves.
- Measurement of tyre pressure and temperature: The sensors measure the tyre pressure as well as the temperature inside the tyre.
- Data transmission to the cockpit: The measurement data is transmitted to a display in the vehicle’s cockpit, allowing the driver to see the current tyre pressure of each tyre.
- Warning of deviations: Some systems also warn the driver when there are significant deviations from the targeted tyre pressure.
- Functionality while stationary: Direct air compression systems also work when the vehicle is stationary and can even monitor the pressure of the spare tyre.
Indirect tyre pressure monitoring systems:
- Use of existing sensors: Indirect air pressure monitoring systems use sensors already present in the vehicle, such as the ABS or traction control sensors.
- Calculation of tyre pressure via wheel speed: Tyre pressure is calculated based on the rotational speed of the wheels.
- Principle: A decrease in tyre pressure leads to a smaller outer diameter of the tyre. This increases the rotational speed of the affected wheel. The system detects this change and interprets it as a pressure drop.
- Detection of consistent pressure loss: A simultaneous loss of pressure in all tyres can also be detected. The system analyzes the vibrations between the tyre and the rim to identify.
- Driver notification: If the tyre pressure drops in one or more tyres, the driver is notified with an alert.
Also important to know:
- Legal requirement in the EU: Since November 2014, all newly registered vehicles in the EU must be equipped with an air pressure monitoring system.
- Benefits: air pressure monitoring systems enhance safety by alerting the driver to low tyre pressure in time. They also contribute to optimal fuel consumption.
- Disadvantages: The sensors in direct pressure monitoring systems need to be transferred to the new tyres during a tyre change.