I've always had good experiences with Mudlites XTR's. It's a good all around tire. Awesome for trail/street riding. Not all that in mud.
On my Z8 I went with Mega Meyham 28's. 1.5 inch thread. So it's a pretty aggressive mud tire. Not as mean of a tire as the top dogs Backs,Outlaws and Terms (2 inch thread). But it's also substantially lighter then those. It's something worth considering, I didn't want to be breaking axels every time I got into a bad hole.