Comment by Animats | Hacker News Reader

Comment by Animats | Hacker News Reader

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Snooping on tire pressure monitors has been demonstrated.[1][2] Range is about 10m with a simple antenna, 40m with a good directional one. Each tire sensor has a permanent 32-bit ID. Tire sensors only emit about once every 60-90 seconds (faster if the tire pressure is low), and only when the vehicle is moving (so the battery isn't drained while the car is parked.) Some can be triggered to transmit by an external LF signal, and this is done at vehicle start-up to get an initial tire check. That mechanism, though, is manufacturer-specific.

As a surveillance system, this has only modest potential. It would be useful to pair this with license plate readers, and notice cars whose license plate/tire ID relationships have changed.

It's probably more useful for taking inventory at car rental lots and finding abandoned/overtime cars in big parking lots. There might be commercial potential in this. Anybody with a big fleet could use something that checks their vehicles as they go in and out.

[1] http://www.winlab.rutgers.edu/~Gruteser/papers/xu_tpms10.pdf [2] http://elib.dlr.de/71397/1/VP_TS_NearctisTPMS_110607.pdf

Honest question to your statement: "It would be useful to pair this with license plate readers, and notice cars whose license plate/tire ID relationships have changed."

How/Why?

Because they generally shouldn't change, unless someone is illegally swapping plates.

I see you have new tires there citizen. Your papers please.

It was poorly worded. TPMS sensors are rarely replaced. I think they have a 10 year/150k mile lifetime.

I have a separate set of Winter wheels which obviously come with their own pressure sensors - so my licence plate/tyre sensor ID pairing will change at least twice a year(I also got a flat once and put a single winter wheel on - what happens then? surely you will get 2 different IDs for one car?).

That's a fair expectation and can be filtered out: you can roughly expect 1 plate to match multiple set of tires. When the same set of tires (or 3 or them) get matched to a different license plate, that can be flagged as suspicious.

New tires won't have been seen on a previous license plate.

Pressure sensors connect to tires to do their job but usually stay with wheels. While not common it's certainly both possible and legal (and sometimes happens) to switch wheels to a different car.

Certainly, but keep in mind no one suggested it was either impossible or illegal.

The suggestion above is to merely take note, as it is unusual.

It's fairly common (at least in Europe) for people to have two sets of wheels, on with summer tires and one with winter tires.

Or legally swapping plates (e.g., personalized plates follow owners to new vehicles, requiring new plates for the vehicle, among other circumstances.)

Or, I suppose, legally swapping wheels, or just pressure sensors.

You don't change plates in the US? Over here(Poland) you get new plates every time the car is sold.

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