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Comment by throw7 | Hacker News Reader

TPMS sensors. A solution to a problem you never had. Congratulations. They have batteries, so it's a gift that keeps on giving.

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Speak for yourself. TPMS is a great feature. Ever drive on a highway that's so poorly-maintained that you find yourself wondering if you're getting a flat? Ever find yourself miles from home with a slow air leak that you need to keep an eye on to ensure that you can make it to the shop safely? Do you enjoy crawling around on your hands and knees with a tire gauge, contemplating the uncertainty principle while you wonder how much air you just let out of your tire while trying to check it?

I've never owned a TPMS-equipped car that wasn't accurate to within +/- 2 PSI in the 30-35 PSI range, and won't be buying any such cars in the future. I see a lot of people complaining about crappy TPMS implementations, but that's something to blame your cheap-ass automaker for, not the technology itself.

There is also indirect method - ECU precisely comparing each wheel's rotation speed, with assumption that lower-pressure tire would have smaller outer radius, thus slightly higher angular velocity. This method is somewhat common with European cars.

It's very cheap (assuming car already has rotation sensors for ABS, and adding a software routine doesn't cost much either), and maintenance-free.

But there are drawbacks, too - it doesn't detect all tires deflating at the same rate. And also, ECU has to be very conservative to avoid false-positives, average a lot, pause comparison when turning, etc. As a result, you only get the tire pressure warning like 10 minutes later that dTPMS would've flagged it.

The VAG system circa 2014 - which i think is a Bosch system used by many manufacturers unchanged, i can’t remember the name of the system but i recall it was version 9.5 of Bosch’s system - was able to notify me of a fairly rapid puncture (hit a pothole at high speed) within around 300 yards. The tyre deflated slowly enough to continue for another 4 miles (albeit at much lower speed) so there would only have been a few PSI lost at the time it triggered.

On the whole in that car (Golf R mk7) it did seem pretty switched on at noticing pressure loss from a slow leak i had after a tire replacement one time, which was handy because the tyres were pretty low profile that meant visual checks were utterly useless. It’d look perfectly fine at 10psi in a tire that should be at 34psi.

One other benefit of the ABS system is that when it goes wrong and the money light comes on, the user’s probably more likely to respond to a “brake service now!” Type message than a “TP-something or was it TS or oh i dont know but the car still seems to drive fine so…”

>contemplating the uncertainty principle while you wonder how much air you just let out of your tire while trying to check it?

This is just a stupid tax on people unable to discern the difference between theory and practice and if anything life needs more of these taxes.

It's absolutely a problem I've had. I drove on a flat for several miles one winter because I thought the sound was just snow packed into the wheel-well, and driving on snow masked the funny handling characteristics of a flat tire.

By the time I got where I was going, the sidewalls were wrecked. TPMS would've saved me a tire AND a bunch of hassle of getting it replaced; the puncture was small and would've been easy to plug if I'd only known to look for it.

I knew a Firestone / Ford Explorer widow. She had a flock of kids.

https://en.wikipedia.org/wiki/Firestone_and_Ford_tire_contro...

How would TPMS have helped the Firestone/Ford issue? The tires weren't spontaneously losing pressure; Ford was spec'ing a low tire pressure and the tread was separating. I'm generally supportive of TPMS but struggling to figure out how your comment is responsive to the grandparent comment.

Tires do spontaneously lose tire pressure. 1-3 psi/month.

There was no margin on tire pressure. TPMS would absolutely have saved lives. General public runs consistently low tire pressure. Source: I am a member of general public and consistently forget to top up. Also, paid my way through college in the 1980s in a gas station back when full service was a thing.

Advocating for blindly making things "safer" with no regard for tradeoffs is like littering in the park. If a few people do it it's no big deal. When everyone does it you wind with bloated cars we can't see out of loaded full of tech that drives up cost, or a trashed park. Thanks for doing your part.

And as the other guy mentioned, TPMS doesn't help you when the spec for the pressure is what's wrong.

TPMS is very important with run-flat tires because you cannot easily tell if one has a puncture or is low on air by looking at it - they hardly bulge at all.

I wonder if you can get a sensor emulator that plugs into a cigarette lighter and you can program the car to read from that. It'd be illegal but you could totally find people who would pay for that.

You can just ignore or tape over the dashboard light instead.

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