Tyre Query

If you want traction (for example winching up wet muddy slopes), then it has to go on the back. But that is the last place I would put the tyre on my mtb. I'd put it on the front instead.

The reason is that on corners where the tyres are likely to skid out sideways, it is more survivable if the rear slides out first. Therefore you want more grip on the front. It is a very common set up for bikes to have a more grippy tyre on the front than the rear for this reason. Typically you'd have a grippy tyre on the front and a faster rolling tyre on the rear to reduce rolling resistance.

So put whatever tyre you need on the rear to get up those wet and muddy slopes, but then put an even grippier one on the front.

Don't forget that grip is provided by more than just tread pattern. There's tyre pressure, tyre width, wheel diameter, composition of the tyre rubber, and let's not forget technique!!