Whick tires would be the best for my z400. I mostly ride in mud and the powerlines. I want something i could use on the track but something that could get me out of the mud wholes.

 

If you ride in a good deal of mud and slick stuff, I was highly recommend the Maxxis I-Razr Radials..... They have far better lug spacing and thus better clean-out in the mud. I've run several different tires and nothing works as well in the slop as the I-Razr. And it also gives you excellent traction in the dry and loose stuff.