The pressure change is by temperature is less than 1 per 4 deg..
To calculate you need degrees Kelvin and absolute pressure (e.g. 30psi is actually 30psi above atmospheric, so about 44.5psi altogether). Then the pressure change is proportionate to the temperature change.
It's about 0.15psi per degree C/K in the relevant range, so 0.6psi per 4 degrees C. If the pressures were set to 30 psi at 20C then at 0C I'd expect a reading of 27psi.
I can't explain why you've had to reset yours twice but if one adjustment was with warm tyres then it will have messed things up.
E&EO. I'm not a real physicist.
My TPM went off last week when the temperature first dropped. They were about 5psi low, probably a combination of the temperature change and the fact that I hadn't checked them for months.
Last edited by: Manatee on Thu 4 Nov 21 at 11:14
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Cold tyre pressures new
Cold tyre pressures new
