Now that I think about it its the 3rd flat on the right side. I replaced both sides with new tires about 9 months ago. got another flat on the right side about 4 months ago. replaced with new and now left is flat again. I'm going to air it up and see if there is a leak but I'm thinking maybe there is another issue. can heat cause this?
Remove tire from trailer, then grab a bucket, add 2 tablespoons of liquid dish soap,
half fill with water. Pressurize the tire, pour soapy water all over the tire and rim.
Look for the bubbles forming over the leak. Puncture, valve, pinch, pitted rim
doesn't matter, soapy water and the resulting bubbles will show the leak.
Once you know where the leak is, it's easy to solve the problem.
BTW, I can't see where the hub or bearings could cause the tire to leak
unless the hub was improperly mounted so that it scrubbed tread off the tire.