I changed tires on the KLR this past weekend. The TKC-80s were very enjoyable tires: Great grip on pavement, given their knobby design, and thanks to the silica in the rubber they gripped well in the rain, too. They were progressive and informative at all times and lean angles, and were very quiet for a knobby tire. You didn't feel like you were riding on knobbies until you got below 5 MPH or so, when the individual knobs striking the pavement could be felt. I ran them at 32/36 PSI (F/R) on pavement.
Off-pavement, aired-down to the low 20's, they worked pretty well, too. I rode about 200 miles of dirt roads on 'em and don't have any serious complaints. Like their street performance, they never surprised me by doing something unexpected, which greatly helps build rider confidence.
The two negatives I found were, first, the front tire's knobs become very sawtoothed at around 4,000 miles. I flipped the tire on the rim for the last 1,000 miles, and towards the end the knobs in the center were getting close to evening out. I shouldn't have waited as long as I did, though, as the reversed profile had very poor grip initially because of the minimal rubber contact. And boy did that front tire howl at highway speeds when flipped!
Second, at $170 + S&H, they were moderately expensive per mile (2.8¢/mile). While the front tire could have gone another 2,000 miles, the rear was down to 2mm of tread in the middle.
Overall, I think they're a great tire for someone who has to regularly navigate the urban jungle—but who wants to get off the pavement without having to switch tires. Or, for someone who has to travel a long way via pavement before getting off-pavement.
For the winter rainy season I've switched back to Michelin Anakees since I have no off-pavement plans until Memorial Day at the earliest. But, I'll be throwing another set of TKC-80s on before I head off-pavement next!