You have to remember you are not comparing apples to apples. This is more of a comparison of apples to lemons. ST tire have a higher load rating and a much lower speed rating? Make sense ? Nope not to me either. The vast majority of ST tires are built in one or two plants in China with a reputation of very poor quality control. the exception is Maxxis. at least their reputation isretty good. speed rating or should i say speed limit on ST tires is another big reason to ahy away from them.ST tires can be hard to find when you have a blow out in some places, whereas a LT tire can be had relatively cheaply almost anywhere. Simply do a web search on ST tire failures, especially on heavy trailers and you will understand why the smart move is to a quality LT tire.
All I can say to the is, if your trailer came OE with an LT tire and your dealer I stalled ST tires, he really did you a Hugh disservice. Plan to sock a lot of money away for when they start exploding at hwy speeds and you need to make a lot of expensive repairs to your trailer. Your going to need it, because the tire brand name will likely no longer be around anywhere.