Upgrading tyre size on trailer..any cons

[Mad Manny]

As long as it fits & doesn't catch etc., there should be no problem.

If anything, it will be better for the bearings as the bigger wheels mean less wear (Because of less revolutions).
The bearings will also run cooler as they work (rotate) less.

[icemanza]

You aren't changing the load capacity of the trailer so the axles should be ok. It is whether the hubs will cater for the tires and whether there is enough space between the tires and mud guards - so you may require leaf spacers.