Just as a quick note, the tire manufactuers tell you NOT to dump air pressure. Their instructions say to inflate the tire to the recommended pressure when it is cold, and then LEAVE IT ALONE.
In this context, the word "cold" does not mean "refrigerated" or "on a cold day". It simply means that you haven't driven the vehicle for several hours, so the tire temperature has come to ambient. The variation in air pressure as you drive it, and as the outside temperature goes up, has already been accounted for. Check, for example, the FAQ from Tire Rack.com at
http://www.tirerack.com/tires/tirete...jsp?techid=147. With respect to pressure change due to air temperature change and heat due to driving, their conclusion is
"Check and Adjust First Thing In The Morning....Do Not Release Hot Tire Pressure if any of these variables could be the cause of measured tire pressure exceeding the maximum psi branded on the tire's sidewall by the 2, 4 or 6 psi indicated above for the various conditions. This temporary pressure increase is expected and designed into the tire's capabilities."
As Rumbleweed pointed out, it is underpressure caused by a leak that is the tire killer. That should be what you are watching for.
Bill