The rear wheel on my single speed has a fixed/free flip/flop hub. I have a WTB Wolverine on there now, which is fine, but less than optimal when reversed. I'd prefer a knobby tire with a reversible tread so I can run it either way with minimal fuss. Does such a tire exist? I was thinking Kenda Small Block 8, but it looks like it is, in fact, directional. Maxxis Holy Roller looks okay, but not particularly grippy in the dirt. Any idea? Oh yeah, 26" is what I need - preferably on the high volume side, like 2.2"-2.3".