Do horses like to ride in trailers attached to a motor vehicle? Do they like moving on wheels? I just saw one on the highway and wondered.

Yes they do because the vibrations they feel on the floor of the moving trailer feels like a hoof massage. 

NO. They would rather pull the damned trailer. How the hell would I know what horses like.

Not all of them and not always.  They get used to it. There are different kinds of trailers with some being more open and comfortable for the horses.  I've read there are some horses that never get comfortable with it.  I don't know if breed has anything to do with it.

Oh for Heaven's sake...I'm hung like a horse.  I don't think like one.

Some do, some don't. 

For the most part to them it is a moving stable. For some who are competitors it is a treat because they are competing.  My old Trachaner loved it, he would be show jumping or field eventing again.  My old Quarter Horse loved it because she would be helping me calf rope again.  Yes I do have an RCA card; Rodeo Cowboys of America card.  In most respects I left the ranch, however I am still a cowboy

I was in the saddle at age 4, competing at age 8.  Next Equine question for $200