The rising and falling gauge pressure phenomenon we see within a tire is a result of changing temperature, according to the Ideal Gas Law, stating that pressure is proportional to temperature. As the temperature increases, there will be a rise in pressure. The cold pressure line is compensated for temperature, however, and should remain flat. Furthermore, on a TyreSense datalog for a fully sealed tire, there should be pressure fluctuations within 1 PSI, proving that the temperature measurements and pressure correlation is exact. If the cold pressure line changes, this could indicate an over pressure or under pressure situation.