Originally Posted by merlinextraligh

My physics is limited to one semester of college physics, so I certainly stand to be corrected. Pressure at sea level is around 15psi. Pressure at 40,000 feet drops to around 3psi.

When the guage on your tire pump reads 100psi, it means 100psi above the ambient pressure. Thus 100psi at sea level would be the equivalent of 112 psi at 40,000 feet in an unpressurized cabin. (As alluded to by Darkmother.)

As for time to equilibriate causing stress to the tube, it wouldn't appear to cause more stress than pumping the tire up an extra 12 pounds.