My KLR had Perelli Skorpions on it when I bought it. Great street tire that sucked in dirt. Put over 7,000 miles on those tires & JUST changed them yesterday. They've still got another 1-2 thousand miles left on them. I went with a Dunlop D606 up front & a Heidenau K-60 Scout on the rear. Haven't had a chance to get them dirty yet but, that should change soon & I'll give an update.
I've heard the K-60 sucks in mud but, the KLR sucks in mud & I usually avoid mud anyway. Dirt, sand & rocks are what I usually ride when off road.