Huntingdog and Tom, this is not about saving money, at least from my point of view. It is about saving lives (especially mine and DW's). So the fact that Airstream uses LT on their best trailers is very persuasive.
On the other hand, the fact that Arctic Fox and Lance (also premium labels) use ST, even on the bigger and heavier units, tells me that ST are not inherently inferior.
As a result, I am not yet going to discard my new USA-made Goodyear Endurance ST tires. They are Load Range D, and my trailer is tiny. They are rated for high speed, and I do not go over 62. I have several tire gauges and use them often. (Did I mention that I am risk-averse??)
But when time comes to replace them (in a few years -- not more than four), I will carefully consider whether LT might be a better choice. A lot will depend on the overall performance of the new Endurance line of tires -- the engineering is different from the Marathons, but it is too soon to say if they are really the best choice.
One more note on the process of online discussion -- were it not for the challenging and probing (and yes, sometimes abrasive!) questions from folks with strong opinions, I doubt that I would have gone to the trouble of carefully cross-checking the recommendations of the various manufacturers, leading to the surprising (to me) discovery that the top firms use both ST and LT as standard equipment on expensive and big trailers.
