Carlisle HD and Endurance came out in the sept '16 and Jan '17.... both are those companies newest gen ST tires. Both have a very good service record so far.
Better service record than Maxxis ST8008 with over 30 tire complaints on this and IRv2 rv websites.
My 1997 11200 lb 5th wheel/5200 lb tandem axles, came with new Marathon ST225/75-15 D. At that time I wouldn't use a ST tire so I upgraded to 16" wheels and LT225/75-16 E BFG Commercial T/A/other recommended LT brands. I'm running in the 51k-54k mile range/7-8 years per set with no issues.
Deleted " a year range"...jim"