That doesn't look like rubbing to me, and may be something else. Can you see on the frame or underbelly of the trailer, exactly where the tires are rubbing? If so, they will be leaving extremely obvious rub marks.
I see this kind of wear pattern on bias tires a lot, as they seem to be more susceptible to axle/alignment problems... as well as bias tires having a different "footprint" on the road compared to a radial tire.
Also torsion axles, just from the way they are designed, it doesn't seem like bias tires do well on them.
I did notice you have Vail tires. There are many under recall currently (see link below), and you might want to check this out to see if yours are affected. Even if yours aren't, they may need to be, which all reports to the NHTSA will help. I would suggest you keep records of everything: