For on the road you have to keep the pressure that high , so no part of the rubber gets to warm so it hardens and damage is done at next bendings of the rubber.
I did some research of how low the tire makers dare to go, and made topic of it.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27477930.cfm
Most important is that you determine the weights on the seperate tires accurate, and that is best don by weighing in the loading you drive.
Then you have to give the speed you wont go over for even a minute in your situation.
Then I can calculate the needed pressure and even can give a range in wich the tires are save and no terrible bumping.
That is to system of the tire makers, as far I have found out right.
Need from tires maximum load and loadkind ( fi E-load) to determine the AT-pressure ( for E-load 80 psi), and the speedcode or maximum speed of tire.
