Most people use a rear tire . Rear tires usually have a more open tread and better front to back grip wile front tires will have better side to side grip.
If you are having your tire slide sideways out from under you a front tire might be better. But if you are loosing grip on steep ups and downs then a rear would be better.
Some people are talking about going down to 2.3" tires and I might give it a try in the spring. I have heard that the Kenda Kinetics sort of sucks but I have never ridden it so I can’t say for sure. Ask some people with Torker DXs I think that is the tire they come with.
I think just as important as the tread is the tyre profile. I’ve found the squarer profile tyres best. Round profiles are unpredictable especially when cornering at speed. They also don’t track very well over soft ground.
I use a directional tyre on my 29" MUni but I don’t think it makes that much of a difference.
New question. I just bought a new Nimbus ISIS 26" Muni that came with a 26x3" Duro Wildlife tyre. As I am only new at uni and am still learning to ride I was thinking of getting a street tyre for it. My question is : are normal 26" tyres that you can buy from the LBS suitable for uni’s or are uni tyres made specifically for them. Otherwise i will have to get a Maxxis Hookworm 2.5" as they are the only 26" tyre UDC has in Australia.