John,
I found that odd too, but I've ordered many parts from e-trailer and they have good specs online, and always seem to be accurate. Yes, typically the ST tires don't have a rating, just industry standard is 65MPH, but perhaps this manufacture is responding to customer demand for a better speed rated tire with now higher Interstate speed limits.. 65MPH is too restrictive.
I'm sure they are still ST, perhaps they are just adding the rating voluntarily to gain a market share. If I did not find the impressive deal on the Hankook tires, I would have ordered these, over the GY Marathons.. the last set has been retired by age and one which began ply separation, and led to broken spring.. granted they did way better than the crappy OEM bias ply tires, but what alarms me is the no warning of an impending failure, the other 3 tires look almost new... and lots of tread. I have not ever seen this with car or truck tires. In fact I just ran a set of Michellin X-Ice stud less tires to the point of baldness and near 10 years, but I had some warning they were done, so could avoid an on road failure. Granted, much smaller, and lighter vehicle, but I'm having a hard time accepting the high rate of failure with ST tires in general, seems LT is the way to go, in my case a XL P-Metric (due to cost savings). In the other thread I discuss the cross section cuts of the GY Marathon, and a P-metric tire, and will try to add some pictures and measurements, but I'm not convinced the ST tires have anything over a properly weight rated tire in either a LT or P-Metric tire of same inflation pressure... I just don't see the ST advantage, they have lower speed ratings, and are not cheaper, in many cases more expensive.. while there are lower cost, higher weight and speed rated LT and P-metric tires out there..