One fact that many choose to ignore, or just don't think about, is that very few RV have the axle load evenly split between axles on trailers or end to end on any one axle. Some owners have learned that there can be upwards of 500# to over 1,000# load unbalance.
It takes more work and effort to learn the reality of YOUR RV tire loading. I and others have covered the how and where to learn the loads on each individual tire (usually not on CAT or similar truck scales).
Regulations are written based on the assumption that RVs have close to perfect weight balance but few owners will make the effort to learn the actual tire loads. Also, those sacred regulations fail to tell the trailer owners that they can expect to need to replace ST tires at 3 to 5 years usage based on the tire DOT serial. You will see numerous complaints about tire failures but most can be traced to overload/underinflation and over-speed or other external damage. There is no "magic" rubber in tires with "ST" on the sidewall but many seem to want to believe there is.
As a tire engineer I have yet to have anyone explain why or how ST tires should be expected to perform better than any other tire of the same size on the road, yet that is what some would have you believe based on their insistence that simply because a tire company makes such an ST tire with greater capacity than their premium LT line. Where is the tire company that makes an ST tire, that will offer a warranty on their ST tires comparable to what they offer on their premium P or LT tires?