in my opinion running ANY tire at its max speed rating and very close to its max weight rating is running on the edge . To me its similar to running a truck just below its max rpm all day long loaded , something is going to blow .
I run LT tires on all my dual axel heavy trailers 12K capacity on 10K trailers ,pleanty of reserve capacity , I run st tires on my light duty trailers single axel ( they are never more than 70% of capacity and local only)
Driving on the highway , I like knowing my tires are rated at 90 mph plus , I generally run with the flow of traffic up to 75 mph , Mostly run 65 , but my equipment can handle the higher speed due to the LT tires .