On Thu, 2 Jul 2009 19:35:44 -0700 (PDT), Tim
wrote:

Well Don, that's what they may claim. But around here, in the late
fall, it seems that when a cold frost hits over night, you can pretty
well expect tires to lose about 10# of pressure a piece.

If the temperature drops the pressure will to an equal degree. Sprint
car wheels have a valve that releases air as the tires heat up, to
keep the pressure constant. When you park it, things cool, and all the
tires go flat.

Casady