Heidenau K60 Tires
We use these tires all the time. We commute on them, we have taken to Alaska in 2011, cross-country in 2010, been on the Triumph Tiger 800XC bikes we borrowed, got over 14,000 KM on that set, got over 19,000 KM on the set after going cross-country on our Beemers and now Leslie has over 23,000 KM on the set mounted on her Beemer. We keep the PSI at 36 most of the times and they seem to not want to wear out.
Revzilla has a good review as always on these tires. Anthony states they are a 50/50 tire. That is how they are advertised. We would call them a 60/40 maybe 70/30 tire. They are not a super knobby so expect a ton of traction in sand and deep mud. Having said that we survived a very wet Dempster and Dalton highways. Tires are subjective and you need to find your way by trial and error based on your riding styles. We commute on these all the time but love the fact that if we want to wonder off-road we have a tire we can trust underneath us.