Nobody wrote: My younger son has a NAPA parts store & tells me that over 90% of on-the-road bearing/axle failures he sees can be traced to extreme overloads and/or poor/no maintenance of the 'rolling' components, regardless of wheel/hub/bearing size.
I learned that the hard way ... but before I owned a teardrop ... I owned (still do) a 4 x 8 ft "utility" trailer (from Northern Tool not Habor Freight) for years ... but was not very good on greasing the bearings. In the end one day while towing it home I started to hear a squealing / screaching coming from the rear. I was only about 15 miles from home and not on the highway so I kept driving. I got home but .... the next time I tried to move the trailer I found that the wheels were WELDED to the axel :-(
That experience has made me be sure to grease my bearings on my teardrop at least once a year (don't take it out that often, nor for long trips)