I confess that I've been driving for years and I still have questions about brake tests.
I have a question about the pre-trip air leakage test. Let's say I've got the system fully charged (~120 psi), I shut off the engine, and apply the brakes. The air pressure drops from 120 psi down to 85 psi, and stabilizes there. Is that when I start timing the system for air loss? Is it okay that the air pressure dropped down to 85 pounds after I applied the brakes? (A 35 pound air drop before "stabilizing").