I would say you have plenty of tire left. Both age and depth.
Being you measured them, I would assume you have inspected them for cracks and so forth.
Numerous sources say a minimum trailer tread depth should be 2/32. Seems a bit thin for me. But they are not steering or traction tires. 6/32" (0.1875) is what I go by.
I would consider changing them out early next season, both from a tread and age perspective.
I am not familiar with this website, but they have the trailer tire wear info well written and is inline with all other info I have seen.
https://www.carry-ontrailer.com/how-...railers-tires/