One of the worst towing mistakes I ever saw, occured just three years ago near my house at a Union Pacific railroad crossing. A pickup was towing a trailer down the road with no safety chains, and at the railroad tracks which was quite uneven and bumpy, the trailer popped out of the hitch, broke the safety brake cable and came to a stop on the tracks. His tow hitch was 2 1/2" and the trailer had a 2" ball, which actually worked until he hit the rough road. We pushed his trailer off the tracks and drove to Tractor Supply for the proper 2.5" hitch ball.