Devil's Advocate:
I would guess that the rear tires we run on our trikes were not designed to be run on the back of a motorcycle. They were designed specifically for automotive use.
Hypothetical Question:
If you were to run your front motorcycle tire on your car, would you run factory recommended air pressures ?? And if you wouldn't, WHY NOT ???
Hypothetical Answer:
Motorcycle Tires are not designed for an automobile, and visa-versa !!!!
Therefor, this an apples vs oranges thread and looking for a non-litigious answer defies logic.