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Discussion Starter · #1 ·
I think this is different to the other tyre pressure threads I've found on here ...

TPMS is supposed to report in-car if tyre pressures change, although it's not clear if that is up or only down?
Aside from that, it would seem obvious TPMS also reports current pressures to the smartphone app?

So how come that smartphone app:-
[1] Reports the below and yet my own hand-held pressure monitor reports: 36.5 FL FR 36.5
[1] Reports the below and yet my own hand-held pressure monitor reports: 37.5 RL RR 38.5
[1] Which ones are correct? And should TPMS have kicked in already? It never worked as expected on my Peugeot 3008!
Tire Wheel Land vehicle Vehicle Automotive lighting


[2] Has taken over 15mins to not finish refreshing with the new readings I'm expecting (even if they're wrong)?

Typically I have taken the pressures at face value across the 2 months I've had the car, when clearly I should've set them immediately using my own equipment to know what my baseline was!

Cheers

Jez
 

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Both measuring devices are probably incorrect. The only way to be absolutely sure is to takes the pressures with a calibrated and authenticated device. However, you have to go with something so I would tend to go with your handheld device. I have never had a TPMS on any car yet that absolutely agrees with my calibrated gauge. Regard the TPMS as a useful guide and warning which is not irrational as the word "monitoring" is key. I have no idea what the Mazda alarm point is but it is almost certain only to be a low pressure warning. I got a puncture whilst driving my wife's car last year and it went off at 0.5 bar below the recommended pressure. (The set pressures are much lower than the Mazda so the MX may have a differential of a bit more than 0.5 bar). You can test it if you are really bothered; just switch the car on and slowly deflate the tyre until the alarm goes off. Also don't forget Boyles law. The tyre pressure rises with temperature so a 3 degree rise in temperature increases the pressure by about 1%. So, if one side of the car is in sunshine then the tyres will show a higher pressure than tyres inflated to the same pressure in the shade. Ideally, pressures should be checked and inflated when the car is not in the sun, at least half an hour after driving it and with ambient in upper teens Celsius.
 

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TPMS in the Mazda only works when the wheels are in motion. That's why you can't get a realtime status update in the app. It would also make Milkfloat's suggestion quite difficult as you would have to deflate then drive a bit to get TPMS to trigger.
 

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Discussion Starter · #5 ·
What kind of hand-held pressure monitor do you use?
Calibrated/ checked agaainst other sources?
A fair question although for a non-car techie like me, I'd expect all tyre air pressure sources to be in the same ballpark given its a safety issue!
In answer to your question, I use this to check pressure, (and I got nowhere informing Halfords that I also use this to inflate my tyres, which rarely agrees with it!)
I'd also note that I got nowhere informing Kwik Fit or ATS Euromaster that the charts they use don't match the pressures on the plate on my car!
 

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Discussion Starter · #6 ·
TPMS in the Mazda only works when the wheels are in motion. That's why you can't get a realtime status update in the app. It would also make Milkfloat's suggestion quite difficult as you would have to deflate then drive a bit to get TPMS to trigger.
Interesting, because having driven my car a short distance yesterday (& forgetting to subsequently re-check), I note today that the smartphone app now reports exactly what my handheld device did once I'd updated all the pressures. :) This suggests that the smartphone app needs to have Pull to refresh applied before driving off to end up with a more accurate value. :rolleyes:
 
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