Humidity makes the air inside the tire to not behave according to universal gas law. If water condenses the pressure drops significantly, if water changes into vapour it raises exponentially (or more). Liquid takes much less room (volume) than gas of the same substance/element. Krzys PS It is mostly theoretical but in airplane landing the temperature goes from -40C to ground temperature (maybe +40C) - 80C delta, approximately 160F delta in few minutes. That may ruin your day if there was water ice crystals that expand into vapour in sub second during the touch down.