One of my trailer tires is wearing excessively on the inside & outside but not in the middle. I know it's not an air pressure problem. There is a little play when I check to see if the bearings are loose. Should there be any play at all?

Not much. I've owned about 8 trailers of different kinds, and I have towed them many miles, and the only thing I have seen that causes a trailer tire to wear on the inside and the outside at the same time is low pressure (or high loads).

Jack the trailer up and wiggle the tire. You should be able to feel something, but if you can see movement that's not good.

Artie

You wouldn't be running carlise tires would you. They did the same thing on my boat and camper . I just got new tires for my camper because all four did that and I don't have that many miles it was pulled. I'm putting tow masters this time.

That wheel should not move at all when you apply side loads to it. The bearing should be tightened enough to be seated but not over torqued to cause excessive wear on the bearing. If you can feel any movement when applying a side load, it is too loose.