Tire Pressure Sensor IDs: Why, Where and When (2015)

https://www.tomorrowstechnician.com/tpms-sensor-ids-why-where-and-when/

by walterbell • 10 months ago

51 32 10 months ago

jsharkey• 10 months ago

A couple years ago I picked up some Autel MX Sensors which support "cloning" through their diagnostic tool. Then I cloned my summer tire TPMS IDs to be the same TPMS IDs as my winter tires, and now I can swap them seasonally in only a few minutes with no need to make the car relearn them.

mystraline4• 10 months ago

Yeah, TPMS and the way its implemented is a BAD idea.

1. Data is not signed.

So data can be easily spoofed and jam up the real sensor's transmissions.

2. Serial number is not obfuscated or in a reduced serial number set.

This allows TPMS trackers to be placed at high vehicle through areas and uniquely track cars. Is dying out due to Flock and ALPRs.

3. Some cars, primarily luxury, will force slow you down to 15mph, honk horns, and go into limp mode.

Note this is trusting unencrypted, unsigned, cleartext data. This is a terrible idea, and you cant turn it off.

xnx• 10 months ago

3. Some cars, primarily luxury, will force slow you down to 15mph, honk horns, and go into limp mode.

I'm surprised some company hasn't sold a "gun" to law enforcement that will disable cars remotely this way.

potato37328422• 10 months ago

TPMS data is "questionable" enough already that no OEM is using it's sudden disappearance as a key do to anything drastic.

I can see them doing it if the data goes from good to bad and then the bad persists over a key off cycle though.

psunavy03• 10 months ago

This is no different than the internet, really. "Hey, we made this thing to operate in a safe environment." Years later: "Oh, crap, what do you mean it needs to be secured?"

henvic• 10 months ago

3. Some cars, primarily luxury, will force slow you down to 15mph, honk horns, and go into limp mode.

Source? I can't find any reference. It looks like you're hallucinating.

mystraline4• 10 months ago

Ah, the new AI insult.

Nah, I'm not providing exploit code to something unpatchable.

But if you use a rtlsdr, read, decode, modify, and then use a Hackrf to generate the waveform... Yeah, it works.

No ai. No hallucination. Just good at signals.

hackernewsdhsu• 10 months ago

TPMS is just another surveillance method. Check your pressure like the old days.

kube-system2• 10 months ago

In the old days people didn’t check them and they’d run around on underinflated tires on the highway until they had a front end blowout and took out a family minivan in the neighboring lane.

That’s why it’s a FMVSS requirement now.

There are secure TPMS implementations, e.g. ABS sensor based systems.

analog31• 10 months ago

Did it have something to do with the Ford Explorer?

But anecdotally, we were driving through Chicago in the family Subaru Forester, and got a huge gash in one tire. The Soob has so much automation in its drivetrain, that it still handled OK enough and we didn't notice there was a problem until the TPMS light came on. We had to cross a couple lanes of very heavy, fast traffic, to get off the road.

potato37328422• 10 months ago

In the old days people didn’t check them and they’d run around on underinflated tires on the highway until they had a front end blowout and took out a family minivan in the neighboring lane.

This is revisionist history through the lens of screeching people on Reddit.

Back in the old days you didn't need to "check your tires" because it's flagrantly obvious visually and in terms of handling when a tire with a 65 or 75 aspect ratio is low.

The reason we have a bunch more requirements on tires is because of all the finger pointing that ensued as a result of the Firestone Explorer debacle suddenly made formerly irrelevant few-psi differences in pressure very important. TPMS is there because you can't get a good visual read on lower profile tires until they're quit low. If you're not oblivious it won't matter you'll feel the vehicle handling funny long before they actually get low enough to cause problems though.

What "solved" blowouts was changes in construction. They started putting a couple extra belts into passenger car tires in the mid 00s. It mostly has to do with cap improvements that help prevent the sidewall from opening up at the shoulder.

Back in "the day" (so like 80s on down) everyone ran their tires to failure (usually bald, but often blowout as well) as a matter of normal practice, bought used tires left and right and blowouts were pretty common, even more common back in the really old days of tubes. It didn't reliably cause an accident unless you behaved hysterically in response, hence why everyone felt fine doing it. But that was so long ago ago, nobody much remembers it, nobody wrote about it on the internet and therefore it doesn't exist for the purposes of online discussion.

lbourdages• 10 months ago

My VW Golf has ABS based tire pressure monitoring and for the most part it works. The disadvantage is that it can only tell you if one tire is flat. If they all get slowly flat over time there won't be a significant discrepancy between tires and they will not trigger any warning.

I consider that a worthy tradeoff though, I can just check the pressure once in a while and I get to save money on my winter wheel set.

GJim• 10 months ago

TPMS is necessary if you have run flat tyres. Otherwise, I agree.

nlawalker• 10 months ago

I'm surprised to not see any mention of indirect TPMS anywhere in these comments.

https://en.wikipedia.org/wiki/Tire-pressure_monitoring_syste...

It has its own shortcomings, but in my opinion they're all relatively minor and it does the job of warning the driver of potential pressure problems without wireless or in-tire sensors that require replacement.

EDIT, never mind, I wasn't seeing "indirect" in the comments but now that I look I do see "ABS", which is what iTPMS depends on for determining wheel speed.

EvanAnderson2• 10 months ago

I've got an RTL-SDR radio listening on 433Mhz near a public parking lot and I can definitely see the comings and goings of individual cars. While I'm sure ALPRs are taking over any TPMS-based surveillance there's definitely a risk there.

Aside: I'll never get another chance to share this, so please forgive the "humor".

Once my wife was driving, with me as her passenger when, the car's TPMS indicator came on. She was concerned and said "There's this 'TPMS' warning light here. What does that mean?".

Without even thinking I said "That probably means something." Likely the greatest accidental fitting of words to an initialism I've ever made in my life.

joecool1029• 10 months ago

I've got an RTL-SDR radio listening on 433Mhz near a public parking lot and I can definitely see the comings and goings of individual cars.

For anyone else looking to do the same with it this project is great: https://github.com/merbanan/rtl_433

EvanAnderson2• 10 months ago

That's the stuff! I've got it doing MQTT into Home Assistant at my house, and CSV into a pipe to a Python script for a commercial temperature monitoring and alerting app. The commercial app is the one that happens to be near a parking lot, but I also periodically get cars showing up on Home Assistant too.

rtl_433 has been great. The ability to capture unknown-to-it signals and build decoders on the command line is really nice. I've got some cheapie driveway motion sensors that I built a decoder for. It was exceptionally easy and all the config was runtime.

lisbbb• 10 months ago

One perfect example of why cars cost so much more these days. It was totally unnecessary, too.

m463• 10 months ago

I find it useful, especially after hitting a bump and getting a punch flat.

In the old days, you had to drive a couple miles to be certain you really had a flat, at which case things were damaged.

BenjiWiebe• 10 months ago

I've had to replace two tires (and I don't drive very much) that would've been fine if I'd have noticed them going flat. But the first thing I noticed was the thumping and at that point they were badly damaged from driving them under inflated already.

There's a third incident like that too, but since I figured out that it had been flat when I started out, that I could've prevented it by looking at the tires (with a flashlight, cause it was dark).

baphomet88f• 10 months ago

Tire sensor component is a wireless component, calibrated to the dash.

A compression test for whether manual transmission engine is capable of cylinder combustion.

Tire Pressure Sensor IDs: Why, Where and When (2015)

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