That's the problem, ST tires for the most part, are not manufactured here in the USA. After getting 3 years out of our stock ST tires, we purchased Maxxis ST tires and have been very satisfied with their performance thus far.
I think we get so used to saying "China" or "Taiwan", it just slips out!
I was firmly in the Maxxis camp until I found out that Carlisle, of all brands, has come out with a newly designed tire specifically designed to handle the heat here in the SW, so I'm gambling on a set of them. They are E-rated with a whopping R speed rating (106 mph), so they =should= easily handle the heat here in AZ. FWIW, I was/am a Chinese-made critic, but I did get 6 years out of my last set of Greenballs, though total mileage was < 4,000. We'll see. FWIW, I do keep my tires covered as much as possible and store the FW on stacked redwood 2x6's. As soon as I can find a local supplier of Aerospace 303 Protectant, I'll be liberally using that, too.
I lost a tire and the tire dealer at the exit ramp sold Carlisles.. so I bought one..
Got home and needed three more.. internet site had them as "R" speed rated, like you I was thrilled.. but I called Carlisle just to be sure.. well.. bad news.. the new Carlisle "Es", and I have four now, are 65mph..