My Visions get about 10,000 miles on the Dunlop E3 tires that get ridden hard on twisties with a 2-up travelling load. I've heard of solo riders nursing 15,000 miles or more!
I'm guessing an R1200RT uses a very soft stock tire composition for better handling - not sure what brand.
Still, for me that would basically be a new set of rubber for every long road trip. Ouch!
