if you have leaf spring axles the bushings may be wearing out

I also had this problem with tire wear, I talked to trailer shop and was told axles should be cambered or bent upward so when youu load the trailer the axle straightens out. If you ever notice an empty semi flat bed they bow upward and when loaded they are flat that trailer is cambered.

When a trailer manufactor buts on a straight axle, when its loaded it will bend downward, which will make tires out of plumb and causing the wear. Trailer shops have a jig the put the axle in lock down the ends and put a jack in the center. You can also do this at home, trailer loaded heavy duty jack in center of axle.

Depending on the entire setup, and the ramps used, the ENTIRE weight of the boat and the trailer is ALL on the front axle when you are cresting a ramp going down, AND you have water weight in the axles and cross members added in when pulling out of the water too, as it drains.

This will do a REAL NUMBER on the front axle in no time. This is why its very important to over-engineer your trailer. I'll say it again: "you can't have too much trailer."

I bought a used boat a few years ago (triple) and one wheel did the same thing. Turns out the spindle was bent and that tire wore out badly.