Check the leaf spring bushings. I was adding aTrail Air kit to the leaf springs and in the process found that the factory uses plastic or vinyl bushing inserts. They were completely worn through. There were not many miles on this trailer at the time. This allowed enough play in the axles to cause abnormal tire wear. The kit came with brass inserts. Easy to change and once it was back together and new tires i have not had the tire wear problem again. It is worth the time and effort and much cheaper than an alignment and may be the problem an alignment will not fix. If the bushings are worn they need to be replaced anyway. It worked for me.