Need to know more about the trailer before I can give you and advice pressure and tire advice.
That is best real weiged total weight or better even Wheel(pair) weights in the loading you drive with.
But as long as you did not weigh the GVWR and for american trailers also GAWR.
From tires the maximum load and pressure needed for that .
Kind of tire ( C-load to E load or ST( special trailer).
Speedcode can be handy too ( J to Q for 100km/62m/h to 160km/99m/h, ST 65m/104km/h)
Give that or put it in my Travel trailer tire pressure calculator , and it gives pressure advice and information about the reserves .
So you can virtually try out different possible tire types and see if they have enaugh load to carry.
But if you let me do it I can include newest idea about maximum load in relation to maximum speed of tire.
https://skydrive.live.com/?cid=a526e0eee092e6dc#cid=A526E0EEE092E6DC&id=A526 E0EEE092E6DC%21348
In this map download first the American version to your computer by
rightclicking and then choose
Download . Other means go wrong like leftclicking or choosing open in Excell or Web-App when rightclicked.
After download and eventual virus check , open it in Excell programm on your computer , but open office CALC can handle it too.
Here a picture of a filled in spreadsheet as example.