With a date of 9/15 everything should still be under warranty including the tires. I would call the selling dealership and the manufacturers rep.
The position of the nut on the u bolt makes me wonder if it is tight. If it slid back some it would cause uneven tire wear an tweak your springs.
I would pull that tire and see if everything is tight and square. Measure distances on both sides. Some axles have a bow in them, but I've never seen tandem axles that are different on the same trailer. I am sure not an axle expert though.
Does the front axle match the rear?
Changing out springs is a very straightforward job.I've done 6 sets as maintenance on my boat trailers in the last 2 years. Saltwater never sleeps.
Good eye finding it.
2014 Silverback 29RE, 2014 Ram 2500 CC 4x4 Hemi 6.4 auto w/ airbags, B&W Companion. Saltwater boats and rum like any good pirate.
Lose the 2nd and the rest will follow.