I changed out my wheels and tires after I bought my 2012 Northtrail FX235 from 14" to 15". All you need to do is check to see if the tire size you want to go to will fit and that the wheel bolt pattern is the same. I was not comfortable with the tires that came on my trailer. Weight rating was barely enough and they wore out very fast. I did a lift and upgraded to the highest weight rating and tallest tire that would fit. Saves your bearings and gives you piece of mind. I found my wheels and tires online for a great deal.
Look online on how to measure your bolt pattern. You may or may not need to do a spring over to get the clearance for new tires and wheels. It depends on how big a tire you want to fit under your trailer.