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How often do Tire Pressure Managemnt System (TPMS) sensors report? Is it a standard value? If not, what's the general range? Also, each sensor has its own ID, correct? Not one ID per vehicle?

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TPMS sensors do not report in real time. Anyone who's make such a statement clearly has a lack of engineering knowledge as it's physically impossible as there must be some amount of time between data transmissions how ever small whether its 1mS, 1s, 1 minute.

It varies depending on the manufacture and type of system fitted. Some systems have sensors in the wheels and some detect the difference in wheel speed using the ABS sensors and steering angle.

TPMS systems the use the sensors in the wheels typically report every 100mS (ten times a second) or some transmit once when the ignition is turned on and then once with every wheel rotation.

FTM (flat tyre monitor) systems use CAN bus to transmit from the ABS ecu and this is usually transmitted every 5 or 10mS

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TPMS sensors report in real time.

For the other questions, I believe it's very manufacturer dependent. i.e. Volkswagen-Audi Group TPMS sensors will report the actual PSI of each tyre, while other manufacturers (Kia, Hyundai, etc) will simply display a warning light when one of the tyres are found to be "low". Hence actual implementation details of the TPMS would be specific to each manufacturer.

I will give you some background information so that you are able to understand more what I mean by the above. There are two kinds of TPMS:

Indirect TPMS

This uses wheel speed sensors. After a baseline pressure is set/found, the sensors measure the rate of wheel revolution. Based on this, the TPMS can determine the relative size of the tyres on the wheel. When wheel speed changes (starts spinning faster than the other wheels), it must mean that the tire is under-inflated as compared to the other wheels. Hence, this reporting is in "real-time", as the changes are measured, and changes are instantaneous. As mentioned above, depending on manufacturer implementation, it may be some time before the result is actually displayed to the driver in the gauge cluster.

Direct TPMS

This, as the name implies, literally uses pressure sensors directly on the tyre, which are sent to the vehicle at certain time intervals.

I should also mention that when I said "real-time" clearly it cannot mean that signals are being sent by the TPMS infinitely many times a second - this is impossible. What I did mean is that TPMS reports fast enough to be interpreted as real time by the human.

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  • Is there a standard for how often they report? "In real time" implies constantly (many measurements reported per second), though I haven't observed that to be the case. – HH- Apologize to Carole Baskin Feb 19 '18 at 0:47
  • @horsehair The TPMS sensor technology will report to the vehicle in real time. Specific manufacturer implementation may not display those results to the driver in real-time, and this could be for good reason. For example, you may like to wait for a number of TPMS reports to compare them and ensure they're the same, rather than possibly displaying an incorrect result to the driver. – WeakMech Feb 19 '18 at 2:12
  • Thanks for the additional information, but I'm still confused. "In real time" to me implies constant sending of information, which would be inefficient in terms of power. The car doesn't need to know the pressure thousands of times per second. What am I missing? – HH- Apologize to Carole Baskin Feb 19 '18 at 2:17
  • @horsehair “a waste of power” so how are they powered? Does each one have a large battery to last for 10 years, or do they get recharged by the rotation of the wheel - in which case power is not much of a concern... – Solar Mike Feb 19 '18 at 6:14
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    @SolarMike - the concern here is the term 'continuous', which from an engineering standpoint implies (to me at least) unceasing communications. This is certainly not the case. There's likely a defined (or undefined, but typical) messages per time unit (e.g. second). That's what I'm looking for. – HH- Apologize to Carole Baskin Feb 19 '18 at 17:31

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