What's the difference between the two? Also, being that I am very new to all this, I am running Kenda Kross tires just to get comfortable with my bike. I hope to move to more dirt in the next few weeks. I live in NY and need a good trail knobby. What do you all think about me keeping the Kross on the front and putting a Kenda Knarly on the rear? I am thinking that the knobs on the side should be fine for most cornering in the dirt. The rear is a different story with traction issues. Also, any suggestions on a good strong general dirt tire would be appreciated. TIA......