I just installed Marathon Plus tires on my Scorpion FX-20. I am new to trikes and have not used these tires before. I have a 3 day tour coming up in a couple weeks that is mostly on pavement, but there will be 7 miles of fairly rough dirt roads. I will be loaded with gear with most of it on a trailer (also never pulled a trailer before). What would be the best tire pressure for these tires. Also, the trailer, which is borrowed from a friend, has 16" tires. what pressure for trailer tires?