Unusual wear pattern ruining trailer tires

Wheel bearings loose most likely. Get them torqued down and regressed. I had the same issue. Jacked up the axle, took of the cover and I could unscrew the axle nut by hand.

 

Hendrickson light weight axle flexes under load. Wheel ends of the axle bend upwards while flexing down the road causing inner tire to wear.

 

take it to a good alignment shop.. they can bend some positive camber into the axle to account for loaded flex

 

Weld some angle iron across the top and bottom of the axle to stiffin it up.

 

MD Alignment recommends the angle iron trick to stop axle flex.

 

Alignments and wheel bearing tightness should be checked occasionally

 

What brand rubber?

 

Axle flex and tire wear

Some discussion about it here, some had success with getting chamber bent into the axle at a good alignment shop.