if trailer tires only good to 65mph, why not switch?

I did a lot of research before ordering tires this spring. I wound up with the Kumho's from Tire Rack for trailers. One reason was because they had a higher speed rating than the others. Oddly enough, when they arrived they are stamped LT and not ST, although they say they are only for trailers. I asked Tire Rack about it and they just reassured me that they are a trailer tire. Haven't put them on yet so I can't give you a report. Others gave them high marks.