Tire PSI seemingly/consistently dropping?

[hydbob]

Not sure about you guys but the eye test works 60% of the time everytime.

 

[Amster]

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.

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.

 

[Worldwide Beagle]

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.

Fwiw, mine were 4 psi off for months. Then, for no reason reason, they were 1 psi off.

I only use them after hitting a big MF of a pothole. I then put on the TP screen and PRAY the numbers, what ever they are, do not change.

 

[Worldwide Beagle]

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.

Exactly! In doing so, you have total control of the situation. The car has been sitting most likely all night, its in the garage and not in the sun. and you can take you time going to all four tires and checking. I know many use Milton pencil gauges. and Jaco makes a good gauge. Another plus, I was taught by my SCCA instructors: when you go to each tire to check TP each morning (while racing) it also gives a chance to quickly eye ball each tire and wheel: looking for cuts, gouges, ply delamination, rim damage, what ever.

Some like digital. I am old school analog. This is the gauge I was brought up racing with, its $39 on Amazon and its GREAT for OLD eyes. Of course, you do NOT need something so fancy. But who needs a Lucid?? The pressure relief button on a racing gauge, like this one, is a great help. I overfill 5 to 10 psi, let the tire calm down, and then bleed down to the correct PSI. Longacre gauges will out last you - and keep working after being run over. A good gauge is lifetime purchase.

Longacre 50417 0-60 PSI Analog Tire Pressure Gauge, 2 Inch Amazon​

AND - I love the clock photo!!!

 

[Cosmo Cruz]

digging up this old thread just to say:

I had a tire pressure warning light on because of the 30 degree (F) temperature swing we get this time of year.

(this happened to me last season, that's how I know to look)

it's 50 degrees F tonight, and expected to be in 80's later today. ( 10 to 27+ in a few hrs...)

light came on when 42 psi was indicated yesterday AM. I run the 21" Pirelli summers at 44 psi cold....they get to 48 psi when hot.

car came with 19" A/S Pirelli but with tire size now in software update I thought this would not effect tire psi warning light ?
(42psi is way too low for the 19" Pirelli )


going to reset tire pressures before I go out this AM. I'm a bit more fussy with the 35 series sidewall tires.