My MH has a 2006 Frightliner chassis w/less than 20k miles on it. I called a Freightliner service center concerned about my loss of air. I was told that a loss of 3 lbs in 10 minutes was within limits.
I recorded my air pressure each hour over 10 hours and found the front and read pressure (dash gauge) went from 100/95 lbs to 63/60 lbs, this made no change in height. After 14 hours the MH did go down in the rear 4 inches, the front had no change.
My air pump gauge on the fire wall went from 127 lbs to 60 lbs over the 10 hours.
Freightliner said my system air loss was reasonable.