Just inflate them to what the sidewall states and move on with life.
More important:
- Look them over for any defects or odd wear patterns.
- Check the trailer lights.
- Manually activate the trailer brakes when pulling out to make sure they are working.
- After 50-100 miles stop and check that everything seems good. Feel the tires and the metal wheel hubs to make sure nothing is overheating and everything with the hitch is still connected and appears to be correct. (repeat any time stopping for a rest break...it only takes a minute or two).