tyre choices

[Greezy56]

I replaced the Primacy 4's with the same. Very stable and great tyre. Conti 6 also good. You get what you pay for!!!

[alan sh]

I wonder how it knew.

[Philr]

The TPMS sensor in each wheel has a unique identifier - it has that to stop the system getting confused when you're sitting in traffic next to another car that also has TPMS as it uses radio to xmit the info to the monitor system in the car.
So if you swap front to back it will know after a short drive that what was on the front is now on the back and vice versa.
Similarly if you swap left to right it will know - beware if you're running rotational tyres that you shouldn't do that as the tyres will now be on the wrong way round.

[Big S]

For information purposes on the end of your tyre inflation valve inside the rim is a small black box that detects the tyre pressure for that particular wheel. It has a small battery in it that sends out a signal to a receiving device inside your car. This is how it knows which tyre is which
regardless of where it is on the car. These batteries have various life lengths some can last up to 10 years according to the tyre fitter I was talking to
a while back. When you have new tyres fitted on a car with a TPMS the fitter will not replace the inflation valve. In a cars later years if a loss of pressure is indicated by the system and you add air and it still indicates a low pressure it may be time to change the TPMS box on that wheel due to a low battery scenario.

[PhilHornby]

I wonder how it knew.

I'm not sure which scheme Hyundai are using, but one method, is the use of accelerometers (See Page 8 of: this document, for example)

The actual sensor is a Schrader "PA6-GF35" (Hyundai 52940-BV100) and appears in the Schrader catalogue at: https://catalogue.schradertpms.com/en-G ... letype=AU] (painfully slow to load, for some reason)

[alan sh]

I am still confused as to how it knows which axle and side it's on.

[Philr]

When I installed an early after market direct TPMS on my race car there was an initial setup procedure which paired the sensor in each wheel to the unit in the car.
If I recall it was a case of installing all of the sensors and then there was a set order to pair each sensor to the main unit. I think it was front left, front right, left rear, right rear.
The pairing was done by forcing the sensor to send a message to the unit by letting air out of that tyre. As the sequence of pairing was fixed and each of the sensors had a unique identifier it knew that, as an example, sensor 1 was front left, sensor 2 was front right and so on. So if I was to swap the 2 front wheels/tyres it would know that sensor 1 is now front right because the unique id moves with the wheel/tyre. It would know this because the sensors do not constantly transmit which is why it takes a bit of a drive for the system to learn where each sensor is, but they do transmit in order. So front left transmits first then front right and so on. If one of the sensors has to be replaced it will have a unique identifier but that won't change the order that the unit in the car is expecting transmissions. So if we introduce a replacement sensor id=5 on the front left it would still cycle in the same order - front left, front right etc but it would now see the order of the sensor idents as 5,2,3,4. The new sensor would have to be paired to the system when first installed as that identifies the sensor to the system and I vaguely recall we had to do all 4.

This was a very early version so I suspect it is a lot more sophisticated now but the basic principles are probably the same.

[Philr]

This link shows how to pair sensors with the main unit.
It seems a lot easier these days
https://www.tucson-forum.com/threads/tp ... -hev.2452/

[alan sh]

You say 'front left transmits first' and then the others in order. But how does the sensor in the tyre know it's 'front left" and therefore has to transmit first? And it you move the tyre to front right, how does the sensor know it's not still 'front left'?

There's something basic I am missing.

Alan

[GrumpyDad]

The Tucson uses sensors and a receiver with an auto relearn feature, rather than the manual or EOBD programmed systems. Which is great for us. My understanding is that Hyundai use TPMS systems from a few different suppliers (Continental, Lear, and TRW are names that I have seen), and they may have different ways of doing things. What does seem to be common, is that they don't make it easy to find out how they implement auto-relearn.

If I was to hazard a guess, I would suggest that they might be able to use some form of signal strength triangulation. Each of the TPMS sensors has its own ID, so they can be individually polled. If the receiver had multiple aerials, it could poll the sensors in ID order, and use triangulation to work out the relative position of the sensor to the receiver. This has got me itching to find out how it is actually done though, so I know what I'll be diving into when I next have a few spare hours.

Not relevant to this discussion, but I understand that Lear are working on sensors that don't require batteries now, which seems like a good next step. Although that just may mean that they are just going to do something similar to contactless cards, and use induction to power the sensors when they take readings.