I had the original Big Horn tires on my 05 Sportsman 500, the day I sold it those tires looks dang near like they came off the factory line, that was after some 6 years of hard riding too. Those were amazing tires.
Now I recall hearing that there were the Original Big Horns, then the Big Horn II - from what I recall the new big horns don't last as long as the original, because they used a softer rubber so they would actually wear out more. I' not totally sure, but if I were shopping I'd still be looking at the Big Horns.
Have you priced with Rocky Mountain ATV?