Good luck you should be able to find many good choices, don't forget tires
tend to deteriorate internally with age so consider if you will wear them out or just have to change them due to age (generally about 5 years). For myself high milage tires
don't make good sense, I camp local so I don't put the miles on them.
Another factor is what percentage of the tires
load capacity your trailer requires. Having a tires with 50% surplus load capacity means that even as the tire deteriorates you still have a good safety margin left. Especially important if you tend toward higher speed driving as heat speeds deterioration. 13 inch tires will run hotter than 14 inch at the same speed.
Your rims will need to be able to handle the higher 50 psi pressure that the high capacity tires require to reach full capacity.
I think most of the people with 14 and 15 inch tires have replaced axle
, one with more "down angle" provides greater clearance to the top of the wheel well. Raises the trailer a bit too. But alas at around $700 it's not in my budget near term.