Originally Posted by CWtheMan
I have asked a tire expert that same question. Because tire compounding is allowed to be confidential no one will give anything but around the bush answers.
Speed rating values are set by the individual tire manufacturer or collectively by an onside authority that has the power to approve such things. In this case, the Tire & Rim Association (TRA). They have raised the bar to 81 MPH for ST tires. Already there have been some ST manufacturers with speed letters as high as "N" on their tires sidewalls.
With the higher speed rating comes the advantage of having a tire that is certified by it's manufacturer to be able to sustain that speed and carry it's full load capacity safely.
Although the basic building materials of a tire are listed on it's sidewall the dimensions are not. Is the cording larger and stronger? Are the other materials going to be more heat resistant? I'm with you and guessing time will tell.
I'm with you on that. Besides butadiene, carbon, nylon, silica, and steel I can't imagine what else there is to do; except different combinations and higher quality control. Does anyone autopsy new tires to compare??