Just purchased a set of Goodyear Endurance tires

Higher speed rating for a load carrying tire is more about the tires ability to cope with heat not necessarily how fast you can drive.
The Maxxis ST8008 are getting a bit dated with low speed ratings.....and not all sizes has the nylon cap that helps hold the tire together which is critical for any tire on a trailer with close spaced axles in the center of the vehicle. Now if Maxxis has worked for you in the past then you don't need a better class of tire.