ST tires are only required ot be Speed Rated to 65 MPH.
No tire company (except for Cooper) has been willing to go the extra distance and produce a better tire.
Coopers marketing structure is what did those Custom Trailer plus tires in before they (the Custom Trailer Plus) could get a fair trial on the open road.
Next, I don't klnow where Buzzy4 gopt his information about R Speedrated Marathons but the goodyear sire still lists them as 65 MPH tires, SEE FOR YOURSELF.
What brochure or website did Buzzy4 get this information from?
Mine comes from Goodyear itself as you can see above in the link provided.