The tyres are 584x54mm or 27.5x2.1" the clearings is really good, much better than on many other mountain bikes whit the right size wheels on..
I only had it for a short test ride today, it feels really nice and it has the smoothness of 29" (622mm) but not that different to 26" (559mm) in handling - for me its way better than 29", i'm 183cm tall and 29" just feels to big - I will need to take it for a longer ride to really tell if 650B is the future...
(A strange thing: here in Denmark we use to call 584mm wheels fore 26x1 1/2, thy were normally used on older swedish bikes like Kronan or Monarch, 27" normally means 630mm wheels thats common on old racing bikes.. so here in denmark we got no less than four names for the same thing 27.5, 584, 650B and 26x1 1/2 great!)