I believe the '04 and up 1950s with the 5500 GVWR had 15" tires.
If for whatever reason it isn't, the only other size choice was ST/205/75R14, so the same width tire except for an inch smaller diameter.
Both of you have mid-model year trailers, so they will probably be the same. I could see the possibility for a difference if one were a very early one, but that isn't the case.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR