Excessive Tire Wear

I had a 1998 Terry 24' pull trailer It had reasonably new tires before my trip to Midwest from Idaho. I put 3,000 miles on it and noticed when I got back to Idaho I had uneven tire wear down to the chords on my back axle tires. I checked my service guy and he said have the axle alignment checked sure enough they were out of alignment. $!25.00 to line up every thing back up. No more problems Trailers often times due to rough roads and loads onboard will over a period of time move axles ever so slightly just enough to cause un-even tire wear and the axles from cargo weight and rough roads will shift alignment