TPMS Basics
A Tyre Pressure Monitoring System or TPMS is an electronic system designed to monitor the air pressure inside the tyre. In the Industrial and Mining sectors, the systems also monitor the air chamber temperature of each tyre along with a host of other features which vary by manufacturer.
A Tyre Pressure Monitoring System (TPMS) is an electronic system designed to monitor the air pressure inside tyres. In industrial and mining sectors, the systems also monitor the air chamber temperature of each tyre along with a host of other features which vary by manufacturer.
A typical TPMS consists of battery-based wireless sensor/transmitter devices, a high-frequency antenna module, and a central receiver. The sensors are directly mounted inside the tyres and are responsible for measuring tyre pressure and temperature, which is then wirelessly transmitted to the server and optionally to an in-cab receiver in the vehicle. The receiver analyses every piece of data sent from the sensors and issues warnings whenever there are abnormalities in pressure and temperature levels.
Although TPMS does not replace manual pressure checks, relying on manual checks alone is not sufficient to ensure tyres are operating within optimum pressure levels. The following is a list of limitations associated with manual pressure checks:
- Pressure can only be checked when the vehicle is parked.
- Possibility of inaccurate readings due to human error.
- Temperature is not monitored during manual pressure checks.
Each tyre manufacturer offers load/inflation tables based on anticipated maximum weight load for each respective tyre size/ply rating. Unfortunately, tyre inflation pressures can change dramatically with ambient temperatures, rendering static calculations unreliable. Some TPMS automatically formulate calculated cold inflation pressures by taking tyre chamber air pressure and temperature into account. Click here to find out more about cold inflation.
The following image demonstrates the pressures a tyre will reach when the temperature rises to 75°C / 167°F. In this example, all three tyres were inflated to 110psi at 0°C (left), 20°C (middle), and 40°C (right).
TKPH VERSUS TPMS
Ton Kilometer Per Hour (TKPH) is a calculation based on the weight and speed a tyre can handle without overheating or causing damage. When a tyre reaches its TKPH rating during operation, it should theoretically be at its maximum operating temperature (critical temperature). The critical temperature for a radial tyre is approximately 105°C / 221°F, and this temperature is typically found in the tread. To date, drilling tyres and measuring the temperature remains the only way to determine actual tread temperature, which is called a heat study.
An Australian mine performed a heat study to compare actual belt temperature levels to suggested TKPH and internal sensor readings. They used four Komatsu 930E trucks fitted with 53/80R63 XDR2 B Michelin tyres. The purpose of the study was to determine whether correlation between TKPH and tread readings or tread readings and internal sensor readings are more accurate. At the conclusion of the study, it was determined that internal sensor readings offer better estimation and fluctuate closer to the actual tyre tread temperature than TKPH readings do.
TyreSense is currently regarded as the world’s most advanced and trusted TPMS system.