There probably several thousand post on here about tires. Go get a 6 pack, and do a search for tires. Bet the beer runs out before you get through reading. Welcome to the forum by the way. Lot of good info. Since you are new, a lot of the questions generally posted by newcomers have already been answered. Please take the time, do a search, and enjoy the results. Also when posting, it sometimes helps to have your trailer brand and model number. Since you posted in the Palomino section, we assume that is what you have, but what year and model.
Now to try and help, all rims have a code on them that tells what inflation they can run at. No, I can't decode it, but it is there, near valve stem usually. Don't buy a tire that you can't put the proper inflation in the tire because of the psi limit on the wheel.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT