How does TPMS work in real time, both the direct and indirect versions.

A diagram of the device should help.

1 Answer 1


Direct TPMS utilizes a small transmitter on each wheel. The device is activated by an inertial switch that turns on when sufficient wheel rotation speed is achieved. This transmitter sends pressure and temperature data to one or more receivers. These systems work well until the transmitters battery quits and then the whole transmitter must be replaced.

Indirect systems have no transmitters. This system utilizes wheel speed rotations sensors installed at the wheel hub or bearing, usually installed first as part of the antilock brake system. The theory is that a tire with low pressure will have a different diameter and therefore a different wheel speed. In practice this system can be prone to false failure alerts. Newer systems have improved algorithms that have a lower false alarm rate.

  • Can you post an image of the transmitter/receiver ?
    – Shobin P
    Commented Sep 4, 2015 at 8:29
  • A quick search for "TPMS sensor" will show lots of images for transmitters. Receivers are specific to each make and model. Commented Sep 5, 2015 at 13:24

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