Why don't the manufacturers recommend LT tires??

Folks I have carried and pulled a lot of trailers & travel trailers, tag along & 5th wheel 35', stock trailers and 5th wheel flat bed for equipment, - small T T and load trailers p tires, 35' T T and load trailers LT tires, when they have st tires as soon as they show wear I replace them. The small ones I use P tires and the large ones I use LT tires. No problems & I feel safe with my choice, what a tire salesman says means nothing to me.