You've just run into one of those trailer gremlins that you don't hear about very often.... Trailer manufacturers don't make their own hubs (so I've been told) and there are actually variations in hub sizes -both exterior where it's visible - and interior where you might need calipers and other specialized measuring devices to find out just how you... got the shaft.... (another of those "ask me how I know propositions"...).
At any rate go directly to whoever built your trailer and find out the specific size hubs you need (including make, model, serial number.... wait a minute I'm getting carried away...). And if the builder is no longer in business find a really skilled trailer shop (the kind of place that will build you a trailer from scratch if you can afford it...) and have your year/model, etc in hand so they have something to work with.
For about thirty years now I've run EZ Loader trailers - and early models came with two different hub interior dimension sizes so you had to learn the hard way... Here's a free testimonial to EZ Loader... My first one only died after 450,000 miles.. the second one I'm running today and it's at about 250,000 miles.... My current one has oil bath hubs and not the slightest problem with them in the 13 years they've been on the road... My daily work schedule as a guide includes almost 200 miles per day to and from either Flamingo or Chokoloskee...
If you were in my area (Ft Lauderdale - and south Broward) I'd recommend Ames Trailer service on Stirling Road....
