Mike,
I can see how your corrections work now. Thanks for the data.
We have taken two approaches to our tire work. Your investigation involves an initial inflation with no subsequent re-inflation as time goes by and data is taken. My data was obtained by pre-pumping the tire to 100 psi before each daily precalibration, with the day's postcalibration falling where it might.
I have been able to wring some information relating to the change of constant with time and temperature changes between calibrations, but thus far I have not been able to make sense out of it.
I am not sure whether you had a specific goal in mind as you did your data collection. I had no specific goal in mind when I began. It was only as the data grew that I saw that it could be used as a fairly accurate predictor of the day's constant. All I need to know is the day's temperature and I have the constant quite closely.
Of course, it would work only for the specific tire involved, and would have no general application. Also, it took me seven years to collect all my data. This might be seen as an undesirable handicap to the usefulness of the method.