That's a good point Winged One... never thought about that.
On our last trip, 6 states, 3400 miles... I saw more than a few fivers and TT's pass me up (and I was doing between 63-65) like nothing, and thought well, they are probably some people who will later complain about cheap tires blowing up.
Regardless of the reason for 65mph, that is what they are rated for, and unlike other ratings, there is nothing that will increase that rating. I guess I'm just not in that much of a hurry while towing to feel like I need to do 70 or 80 down the highway, meanwhile risking over-heating the tires.
I find it interesting that the weight police are so adamant about the ratings manufacturers indicate for weights and say we should all stay well under those weights, but when it comes to tires, the China Bomb police totally discredit the speed and weight limits on tires and call foul.