I would have never guessed that a tubular axle could be bent but I had my trailer axles cambered a few weeks ago. Very reputable, small independent shop in my area. Said they do it pretty regularly on new trailers. Axles built to be straight but need a little camber to off set loaded flex.
You could try researching "axle truss". I'm with Swaan though, proper spec axle shouldn't need it. Unless it was a poor design from the start.
Can I.get the name of the shop? I have a 2019 Hyundai dry van that has this issue. All inner tires have heavy inner edge wear and looking at replacement of all 8 very disappointed as it was a new trailer and Virgin tires needing to be replaced at 200k. Center tread is still 50% I've thought that it was poor wheel bearing end play but after further investigation its axle flex. It is a tubular Hendrickson air axle. Still under warranty but no clue where id go to get this issue addressed
I have added the long angles on my axle. It seems to have worked so far. Ran out of daylight and didn't add the short angles. I have 146500 miles on the tires so far and they are wearing good without cupping so far. As I understand it, the 6 " axle was made with a thinner wall thickness than 5" axle, therefore the flex as it goes down the road.
The issue is real. Bought a brand new van trailer several years ago with this Hendrickson axle and had the same tire wear problem.
Soooo……five years later, has anyone welded angle iron to their axles with any success yet? I’ve owned this trailer for 12 years and it’s been wearing tires funny since new ( I’m the only person who has ever pulled it) and alignment is near perfect.