I've got the K60's on one of our F8GSs and I've put about 6500 highway miles on it in the last two months (I wish it was more weekend fun miles instead but I've had a hell of a commute waiting to close on my new house..) and there's still plenty of tread left. It's just now to the point that if you stare at the profile you'll start to notice where it's getting a flat spot. Over 90% of that mileage is spent a 80+mph for long durations. I'm easily gonna get 10K outta this tire. One thing to note about the 140 rear: Because it is a taller tire, expect more lean when on the side stand. I'll probably go back to a 150 when this one's spent just for that reason.
Temple, TX -> Cape May, NJ -> Mobile, AL -> ECity, NC -> Kodiak, AK -> Mobile, AL -> Sacto, CA -> Cape Cod, MA -> New London, CT -> San Francisco, CA -> Juneau, AK (summer of '13) -> where to next?