Dropping tire pressue on dirt
A few of my favorite destinations require 20+ mile drives on dirt roads that can have pretty bad washboards. This year, I want to experiment with dropping the tire pressure when I embark on these roads, and of course airing up when I leave them.
I'm wondering what sorts of guidelines I should be following. I run endurance's generally at 65psi on the pavement. If I limit my speed to say 20mph on dirt, how low can I safely drop the pressure?
Any guidance on this would be appreciated!