The TT owner's manual clearly states that the TT tires should be run ay 65 mph or less. The tires are rated for service at 65 mph. There is no indication of what their maximum speed is.
It is assumed that the TT will see continuous service at 65 mph on Interstates, and other limited access roads that allow such speeds, hence that is the service rating of the tire.
Those who choose to drive faster for whatever the reason, will most likely find the problem is not driving fast, it is stopping all that inertia. A lot of pavement passes under you rig before it comes to a stop.
Take care