Over 30 rv website members have reported issues with their Maxxis ST8008 tires. Their a bit dated as all sizes don't have the tread stability belt and their still 65 mph speed rated. Speed rating is about the tire ability to cope with heat.
I would look at the new gen Carlisle HD.....or Goodyears new Endurance....or the Provider by Taskmaster if your wanting to stick with a ST tire. All are L and M speed rated (75-81 mph).
The Providers have been around the trailer industry for 6-7 years now and some say they are OEM on larger trailers. They seem to go the distance.
Your Carlisle are the old style even before the much improved RH series. The Carlisle HD has been out for about a year.
The Endurance is a new ST tire that replaces Goodyears very old Marathons
And of course depending on your tire size and load range and axle rating a quality LT would be the best upgrade for 40k-60k miles and 7-10 years.