At the risk of seeming to agree with the NMed, I have purchased many new trailers of all types, 4 being RVs, and none of them came OEM with tires/wheels balanced. If I did replace tires (rarely), before buying another new trailer, I did not have them balanced. My reason...same thought as JIMNLiN back on page two.
I see friends posting here, that are somewhat adamant about balancing trailer wheels. That's OK, I'm not saying you shouldn't! However, for those willing to look back at Jim's reply on page 2 of this thread, I agree with him, concerning actual need.
I am anal about vehicle tire, and especially high performance motorcycle tires being balanced.
Jerry