Heartland Manufacturing touts ST tires also but on their forum there are many, many post about people having blowouts with ST's and going to LT's and it solved their problems. I went with LT tires designed for trailer use only.
Interesting! A year ago I bought a new Big Horn Heartland 5th. wheel and the trailer had Tow Master tires on, I told the sales person that I would not accept those tires. The salesman, said no problem, Heartland would install different tires---LT Good Year G rated tires. I have used Good year tires for years and have had good luck.