Had the same issue, same trailer, same axle, same salty conditions. Dry wight AS175 with engine weight is only1400 lb +-. I kept wondering wondering why I had to keep replacing tires. Going to the ramp the wheel broke off right at the axle. 3500 lb axle should support that weight. It rotted from the inside out. Everything looked fine prior to that moment it broke. Would have been disastrous if it happened running 70mph down the high way. You just need to be sure.