To answer your specific questions above:
Yes this was asked
their answer was I would be insured however,
and there always seems to be a however...
"The specific design of the ST trailer tires side wall is such that it will withstand flexion and side wall impacts to a greater degree than LT's.
Curb scuffing plus up to 90 degree spot turns aka scrubbing twists ST tires core design - something which P and LT truck tires would not be exposed to on a repeated basis...."
Have to wonder where that person is getting their information. Can they point to any industry standard of government regulatory test for the above conditions? IMO this sounds like a nice excuse to deny coverage while accepting no responsibility for demonstrating a tire is capable of passing some fictious test criteria.
"Whereas ST tires are industry designed for Travel Trailers and LT truck tires are designed for trucks and not trailers- there is no manner in which we the underwriter can insure that if you have LT tires on your trailer that they have not met with a degree of normal use that would not have caused the failure to which an ST trailer tire would have withstood."
In our remembering that the tires replacing the originals must meet the
Gross Vehicle Weight (GVW) limits specified by the manufacturer (found on a decal on the trailer) made up of the unit itself plus the actual weight of the items used to fully load the trailer, including all cargo, fluids, and optional equipment, as measured by a scale.
on the 2012 Salem we had the original tires were a bias ply -
swithed to radials but in a Eurometric "E" rated tire which surpassed the original tires in both weight and speed capabilities.
Another thing that was mentioned by 3 tire businesses here was that
a one spec size wider on the rimsize would add stability to the trailer. As a result 2 dealers spec'ed my original rims out to see if they would support for air pressure increase with that different tire config.
I was also reminded that increasing air pressure does not increase load carrying ability of the tire...
Have to wonder if the person writing this has informed the US Tire & Rim Association and the equivalent organization in Asia JATMA or in Europe ETRTO or the US DOT that all their references to Load and inflation tables is wrong. I would really enjoy having a discussion with that person.
Whereas the replacement tires exceeded the manufacturers minimum specs for both weight distribution and speed capabilities and the rims were capable of sustaining the air pressure increase - if we had an accident - we would be covered. The eurometric tires are used overseas for trailer towing and commercial applications. They are different than LT truck tires.
For the 2009 Sundance - heavier trailer
No LT tire would match the weight classification in the 225/R75/15 tire size. Close but with the loaded amount - just short.
so we had to settle for ST's.
We tow with a TST monitoring system and watch the readouts as part of my cursory checks while driving.
I've seen no appreciatable increase in tire temp if hauling at 110 kms an hour vs the 104 (65mph). Weight is distrubuted as even as possible.
Insurance claims are one of 3 things you can't cheat on and they will always get the better of you in their favor.
The other 2 are Death and Taxes.
i guess as far as my family is concerned if the tires i am replacing with are a better standard originally used, (and that includes the side wall configuration as well as load capacity and speed rating) then it makes sense.
To merely switch from an ST tire to an LT tire because I can get more speed out of it but loose the sidewall durability - I'll choose my tire wisely for my families sake and the sake of safety to others on the road.
I'm still suprized that some manufacturers are legally permitted to use bias ply tires.