OMG... We go through this dance every time the questions about tire pressure comes up.
First and foremost, for a number of reasons besides tire pressure, Ya gotta know the weight
of your trailer and tongue weight
when loaded and ready to go. If in doubt, follow (a) below for tire pressure.
a) I have yet to find any proof that running the maxmum pressure shown on a side wall has any negative effect on tire life or tracking, It may make the ride firmer, but that's about it. I have personally contacted Michelin and Yokohama with this question and they concur.
b) All tire manufacturers have a load vs tire pressure chart available and, as mentioned, the pressures shown are MINIMUM pressures for those loads.
c) To drive and "Feel" a tire's temp to determine if the pressure is correct is just not as accurate or as safe as using a manufacturers table, and there is no evidence available that a "Cool" tire is a bad idea anyway.
d) And even the thought of using any tire for 10 years scares the bejezzes out of moi. Tire failures on the road can not only be dangerous & expensive, they can cause considerable damage to your rig as well as collaterial damage to those around you. I pull off my tires
, regardless of appearance/miles/condition, shortly after their 6th birthday and refuse to drive or tow on any over 7 years old.