Someone somewhere from an airline (and a cyclist) posted the fact that animals travel in the cargo hold. The area is pressurized else they might die. He said it's okay to leave tires fully inflated.

Having said that, I'll drop them to about 80 psi. Enough to cushion, hard enough not to pinch.

I pump up my tires every time I ride. My tires (butyl) lose perhaps 20 psi overnight and I have a pump that doesn't lose air when I attach it (so it's not the pumping that loses the air).

The latex tubed tires lose air so much that I have to pump them up, even if it's only several hours after my previous ride.

+1 on the reasons for deflating silk tires. Now with much tougher and stretch resistant casings, not as much an issue. If anyone ever saw an older Clement Criterium Seta that looked like a 700x32 would know that they stretch quite a bit.

cdr