Warranty coverage can be a bit dicey anyway from what I have seen. For instance, BFG ( and perhaps others ) have limitations on their stated warranty if you are using the tire in "commercial applications".
Whatever. I consider warranties to be mostly a useless "feature". I have often said I would buy a given product, and they could keep the "warranty"....and just discount the purchase price for me. I'd come out ahead in the long run, I am totally sure of that.
Using "warranty" as a buying decision, for me, is a non-starter.
In other words, as all this relates to the debate of ST or LT tires on my trailers ( y'all will notice I said "MY" trailers......let me make it clear here that I really could give a fat rat's pa-tooty what tires anybody else runs ), I could care less about the warranty. I just know what works for me, and people I know, so I go with the best I can for the job at hand. All my trailers run LT, of various brands. And are approved by the trailer manufacturers.