I've had my K75s for two years now and have put 18K miles on it in that time. Mostly commuting, but lot's of short hops and burns around the town and on one or two day highway trips. I never ride two-up and usually ride with a few things in my side bags.
The bike has had Battleax BT45 installed for the entire time and I've been through two sets now. I know I'm swimming against the stream here but I don't think I like them.
In both cases the front tire was replaced because it was badly cupped, and that was the case with my first rear as well. The second rear tire just popped on me, leaving me stranded. It was worn down fairly well, but nowhere near corded. It's not clear yet why it popped, I haven't had a chance to take a close look yet. A brief look showed nothing extraordinary.
Anyway - If I'm going to switch tires this is the time to do it. My third front tire is cupped again anyway.
I'm thinking Metzler Lasertechs - but I'm quite open to suggestions.