Not sure about you guys but the eye test works 60% of the time everytime.
I never knew how they worked. Why do you have to reset the TMPS in the car when you change tires? Or in my last car, if they sent out a low warning, when you filled it up, it would still give you a warning light until you went into settings and manually reset it.The pressure sensor is filled with a gel that is exposed to the air in the tire. That gel transfers the pressure to the sensor and protects the sensor for all sorts of nasty stuff in the tire like water, latex flat fix, cleaning solvent, bead seal, grease, etc. Don't even ask what happens to the gel during a Rapid Decompression Event, aka blowout.
Fwiw, mine were 4 psi off for months. Then, for no reason reason, they were 1 psi off.The temperature thing makes sense. I was raising an eyebrow to the Californians claiming these things are accurate, where mine are often as much as 3-5 psi off. Other times within 1 psi, other times spot on. Etc.
@Worldwide Beagle hit the nail on the head: consistency is what you want from any tool. And consistent these are not.
They did do their job and throw up a warning last year when the techs at Discount Tire put on my snows and then only inflated them to 42 psi. But that’s about all I’d rely on them for during a Colorado winter.
Not every broken clock...
I think we all learned a lot about TPMS today so thank you. Based on what I learned, it sounds prudent to externally measure and set your tire pressure with an accurate reader probably every 2-3 weeks or when there is a big weather temp change.