I've never found leakage rate that varied with load. Think about 50 psi inside the entire carcass vs adding 250 lbs of load to the tire.I checked the tires and they state 50psi as the max in my case. Pumped them up a few days ago, and planning on strapping the bike onto the trailer tonight to see if it holds with the weight on. Of course my stupid pressure gauge failed when I need it.