Just my 2 cents here, but ST trailer tires
are not really needed for a 13' Boler.
Standard passenger tires
such as 155/80R13 79T SL are more than sufficient for the weight
of a Boler. The 79T is the load rating for each tire (963 lbs.).
So if your total trailer weight
(less tongue weight) is less than 1926 lbs and it most definitely is (my 74 Boler weighs in "wet" at the scales at 1050 lbs, including tongue weight
, as in not hooked to the TV.). When I say "wet", this is packed with food, coolers, bedding, camp chairs, etc. good for a 2 week run.
Further, I have run 155/80R13 79T passenger car tires on my Boler for the past 24 years (not the same set) with no problems. Always end up changing the tires due to age related cracks, not wear or failures of the tires.
Something like this would be fine: http://www.tirerack.com/tires/tires....te&autoModClar
Now if I was putting them on a utility trailer and expecting to dump a couple of yards of gravel or a hundred 2X4's on the trailer, I would definitely be recommending trailer rated tires.