Mike
your posting Discount tire info on the speed rating (N= 87 mph) which isn't on Carlisle RH website. In fact all we see over their on their warranty page says quote;
***The Warranty is void if the tire or wheel fails due to damage from improper inflation pressures, exceeding the maximum speed limit, or overloading the tire beyond the maximum load capacity stated on the sidewall.***
– Best practice. Do not exceed 60 mph while towing a trailer.
– Most ST trailer tires have a maximum speed rating of 65 mph.
Check to your satisfaction