TPMS is an electronic system utilized to monitor air pressure inside each wheel and suggest the driver if it finds pressure difference between the four tyres. It indicates the driver by illuminating the tyre cross section shaped symbol on the dashboard with exclaimation mark in between.
There are two types of TPMS systems, Direct (dTPMS) and Indirect (iTPMS).
- Direct TPMS
- Direct system utilizes pressure monitoring sensors inside each
- . These sensors collect the data and sends it to the common control module that is connected to it wirelessly. Now this module compares data from all four tyres and alerts the driver if it finds low pressure in any tyre.
- Delivers actual pressure reading.
- Not affected by tyre condition
- No need to reset after checking pressure
- Expensive option compared to indirect system
- Although the battery lasts for about a decade, if it is drained, then the whole sensor needs to be replaced.
Read more about : Effect on Tyre’s Air pressure due to Temp/Time fluctuation
- Indirect TPMS
- Indirect system does not have proper sensors inside the wheels, but utilises the pre-existing Anti-lock braking system sensor. The ABS sensor records the rate of revolution of each wheel, and an onboard computer compares the revolution data of all four wheels with each other. It works on a simple concept that if the air pressure of the tyre reduces, the overall circumference is also reduced. Smaller circumference means more revolutions for the wheel at a given speed. So, indirect pressure monitor does not exactly measure the air pressure but compares the revolutions of each wheel. If one wheel’s rpm is greater than the other wheels, then the system gives the low pressure warning.
- Cost effective compared to direct system
- Negligible maintenance issues
- Shows unreliable data when tyres are worn out unevenly
Although the convenience of the Tyre Pressure Monitoring System can’t be matched, it’s still a good habit to check your tyre’s air pressure manually.
Read more about : Importance Of Maintaining Correct Tyre Pressure