Dropping tire pressue on dirt

[afk314]

Hi everyone,


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!


Thanks,
Adam