Is it standard practice to balance trailer tires?

[Riwright]

After I got some new tires it seemed to me that I was experiencing an increase in the number of loose screws. I wondered if the trailer tires were balanced properly. I looked over the tires and could see no balancing weights at all.

I called a tire place and told them I wanted to get the balance checked on my trailer tires. They seemed puzzled that I would want that.

Is it standard practice to balance a trailer tire or do they just slap 'em on? Do you have to ask for them to be balanced?