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Comment by oneepic | Hacker News Reader

What is the make/model, so we can avoid/be wary of it?

I edited the post to contain that info (a Kia Ceed) as I'd want to avoid that myself too. But sadly I think that means avoiding 90% of all new cars nowadays...

I was reading it and said to myself "geez, sounds like that Kia minivan I rented". I got to the end and was delighted.

The two cars I actually own, a VW and a Toyota have much better experiences in my opinion.

JFYI, you can call yourself lucky with engine starting, the new i20 (Hyunday, so from Corea as well) in order to start needs:

1) neutral

2) clutch depressed

AND:

3) brake depressed (hand brake pulled doesn't count)

also I suck with car knowledge, but I believe the hot tire pressure is different from when they're cold. Perhaps the car's software doesn't take that into account?

I believe air pressure increases with temperature, which shouldn't set off a low pressure warning.

I wonder which style of tire pressure monitoring they're using.

One is to measure the output from the wheel speed sensors. A difference in speed is assumed to mean a difference in size. A smaller tire must be a low tire.

The other is to have actual sensors in the tires that read pressures. They're usually paired to the car.

I have a set of tires (with sensors) in the garage that my car will pick up from the driveway. The sensor reads and everything looks great. The alarm will go off to tell me the sensor isn't reading anymore a few KMs from home, and it is correct.

> The other is to have actual sensors in the tires that read pressures.

Hell, my car (admittedly a performance vehicle) will give you exact PSI, but more than that, even gives you individual tire temperatures.

Raising the temp raises the tire pressure, so that definitely shouldn't cause a low pressure warning.

But, broadly speaking, definitely sounds like they didn't take something into account w.r.t. hot tire pressure. Maybe the tire sensors are throwing a warning because the temp is too high, and the software is incorrectly displaying it as a low pressure warning, or... or some other hellish combination of failure.

> the software is incorrectly displaying it as a low pressure warning

The post doesn't specify if the display actually says low pressure, or if the TPMS warning light comes on, which we usually interpret as low pressure (most common case). If it is the TPMS light, I'm sure that's more of an "out of range" warning than "low pressure."

The post specifically says, "It complains about low tire pressure" so I took the author at their word.

But on the other hand, you may be right. Maybe it's just a TPMS light. It's a fun ranty blog post, the author wasn't necessarily being super precise with language =)

But the other other hand, not all TPMS systems can detect overpressure (indirect TPMS only detects underpressure)

Yeah, friction heats the tires (and air inside them) when being driven, more so with more speed and time, creating extra pressure in the tires. I've had my car complain to me about tire pressure a handful of times, only to check the pressure and noticed 3 more PSI than usual in one tire, all others OK.

Some cars use "indirect TPMS," which means instead of a sensor in the tire's valve stem, it measures the speed of each wheel and uses some fancy math to determine if the pressure is low.

I'm not sure if the Kia Ceed is one of such cars, but if it is, there may be some wackiness in their indirect TPMS system. Especially considering the OP says it only happens after prolonged driving at high speeds.

My wife's 2015 CRV works this way.

We've verified with three tire pressure readers that all the tires are the exact same pressure (within ~0.5 PSI). We've manually done the magic to reset the computer.

The TPMS system light still comes on after a few minutes of driving. Dealer service department has no idea what's wrong.

hot air=denser. When tires travelling on road, rubber get hot. Hot rubber make hot air.

So, "low pressure" after an extended drive is opposite of expected behavior. More common that you prolly run into yourself is the low pressure light in the mornign when it's cold, that then goes away as you drive for a little bit.

seriously, why would you avoid naming whilst shamung?

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