Bird, Depending on intended use, balancing trailer tires can be a good thing. Although I don't think it matters for slow travel especially intermittent use, highway speeds and extended distances argue for it. The trailer manufacturer where I bought my last two trailers, custom to my desires, didn't ask if I wanted them ballanced. They just do it with wheel weights. They do ask if you want 15 or 16 inch rims and if you want used or new tires but they ballance everything, I think.
I go with new 16 inch load range "E" and a spare.
My 1 ton Cummins/Dodge has been upgraded to 19.5 Alcoa Rims and Michelins. They came with a balancing powder in them. I was skeptical but after 60,000 miles the tires are wearing very evenly and I can see that they will certainly rot off before they wear out. Just speaking figuratively. At some point I will access the condition of the sidewalls and decide to replace them but not for a while. The tires are aboiut 9 years old and have about 1/2 of the tread left. I use an ultraviolet and ozone protectant on them so they are not deteriorating as fast as unprotected tires. This is a brush-on product I bought at camping world. I am quite pleased with it.
Pat
Pat