Looks like someone hit a curb and bent the axle. When I bought my AT one axle had this wear pattern, but on the inside. Wore a tire out on the trip back from Virginia. I removed the axle and took it to my local axle shop and they straightened it out. I believe it cost me $135. Has been good for 2yrs now.

Yep, I went through the same thing a couple years ago and was a bent axle, although my car hauler had cheap tires on it that were separating and looked the same way. Once I replaced the Chinese tires on the car hauler they never had problem. I'd replace a tire or put the spare on and see if it starts again before swapping the axle. The axles are fairly inexpensive but they will need all the dimensions to replicate.

Does the trailer track straight behind your truck? Measure the spring hanger (the brackets that are welded to the trailer) locations and make sure they are the same on both sides.

Also, measure the from the coupler to the axle on both sides. The axle(s) could have slid on the springs.

Trailer Axles should also be aligned, better to align them on trailer with all axles. Harder to find people with knowledge and ability to do a correct alignment. Even new axles need aligned!

One issue is low tire pressure or tires overloaded, see wear on inside as well as outside, the worse outside wear would have to be to much positive camber. A trailer axles are built with a arch in them to ride true when loaded, on level ground if you can get hold of a camber gauge an ck to see where it is. If its over 1/2 degree + , going to need to replace the axle(s) as the only way to align a strait axle is bend it, and if only one side is out even tuffer to do one side, not sure where you are I do have the gauges to ck this if you are close enough to run by one day.