Trailer Tires
Beside load capacity. The most important thing to care about is the age of the tires.
Check the DOT''s to make sure the tires are new when you buy them.
Make sure they are inflated properly as heat is the enemy of all things, especially rubber.
Keep your speeds down as the faster you go the more heat is generated in the tire. That is the reason for speed ratings.
I know nobody does it but there is a very good reason that most states limit the speed to 55 mph when towing.
Things like stability, braking distances to name a few.