Well, I followed up on Huntingdog's suggestion, and I am surprised:
One model of Airstream, the Classic, uses LT tires. Almost all of the rest of their models are ST. This info is on the "Features" link for each model. The other exception is the little Basecamp, which uses 18 inch (!!) Goodyear Assurance tires. Not sure if those are LT or passenger tires, but they are not ST.
All Arctic Fox models, both trailers and 5th wheels, use ST. See this link and scroll down to the end:
Arctic Fox Brochure The biggest Lance trailer I could find, the 2375, uses ST tires.
So this tells me something: first, the fact that Airstream uses LT tires on its biggest model means that LT tires are not unsuitable for towing. Airstream would not steer its customers wrong on a $140,000 trailer.
Second, the fact that almost all of the other high end models by Airstream, Arctic Fox, and Lance (three of the best manufacturers) use ST as standard equipment means that these luxury-market firms are happy with ST, which means that ST is probably not just a low-cost alternative.
Frankly, I expected to see LT tires on some of the big Arctic Fox units. They are known for building rugged trailers that go off-pavement.
So, based on the behavior of the trailer manufacturers (rather than the tire manufacturers, who are just responding to the trailer makers), I conclude that ST tires must be ok for most applications, especially smaller single axle trailers. But the fact that Airstream uses LT on its biggest unit means that LT tires are also ok, at least on large dual axle trailer. The caveat, of course, is that these would have to be high-quality tires, in either case.
That is not where I thought this discussion was going!!
