A lot depends on whether they're tube-type of tubeless.
With tubes I've heard reports they're going around 10Kkm range. Doing fairly well for a tube type.
I agree with Tarmo. Sets of tubeless under my 1100 go up to amazing 30Kkm front and 20Kkm rear. The wear of the rear is in direct correlation with your right hand's attitude of course. Some rears I've worn through less than 13Kkm.
They don't want to go much over 150kph, although indicated max allowed is 160kph, especially in the hot conditions. I killed my rear in Iran after speeding in the mountain roads, the mantle cracked and throw away bits - Heidenau compensated a new rear tire after my complaint and they've changed the compound mix after that - a bit softer to improve the integrity. So good for us, for going through fast roads in Europe into the third world, where you need to go slower and have more offroad capability. A perfect tire IMHO.
The new compound apparently does better. After constant 150-160kph haul almost full day last summer trip to Syria, two up full of luggage the mantle had some cracks after returning home, but hasn't thrown away anything like the older version did. But it's a thumbs up in the end - compared to any so called "dual sport" tire, which normally is a full dissapointment in the soft stuff, K60 is knobby type of a tire that holds your rubber side down!
They're a relatively temperament on a wet tar, but then again, any knobby type of tire is. Also in tubeless 100/90 19" version, you need to fit the front tire wrong-way-round to match the pattern.
One thing is certain - they're the best bang for the buck in tubeless form as a real
dual-sport tire. Funny thing is lot of people now use them in tubeless version, although they aren't exacly the correct size for the GS spec. I remember I was one of the first to put them on as an experiment, and after my report to ADV rider they've now spread everywhere, despite their size is a bit "wrong", but the good thing is you normally hear very good words for them, especially for traveling use where you need the grip both in dirt and tar, and while they should last. That's what the K60s are all about - a much cheaper alternative for popular but expensive Conti TKC80
Hope this helps, and ride safe, Margus