Thank you for your help. I went back and checked my pictures that I took and they are D13 that are currently on the trailer not R13. What i still find troubling is that even the load range D tires in the current size will barely meet the GAWR of the trailer (about 50lbs above the rating) but is about 500 lbs short of the GCWR. I have to wonder if this is why the outer edges of the tires are wore down to nothing while the centers are still good. I know that they aren't under inflated because I just checked them and they are still at 65 lbs.
It really shouldn't be my concern since it isn't my trailer, however since I have offered to tow it to him (about 200 miles) I want my family to be safe when doing this. Maybe I am just over thinking it.