Depends on the type of mud you're faced with.
Ideally for "bottomless" mud, you want your tyre to be able to float, rather than cut through the mud, thus low tyre pressures up to 0.6bar would be ideal and will aid in the tyre "floating" on the mud. The opposite also holds true, if you're faced with shallow mud that has a firm ground underneath, you'd ideally want your tyres hard to cut through the mud and obtain grip on the harder surface underneath. Well that's the theory. When I see mud, I normally don't stop until I'm well and truly stuck

instead of trying to avoid it. A friend of mine was stuck for 3 hours in a mud pit with his Frontier - eventually the farmer had to bring his MF Digger loader to pull the Frontier out. Even then the MF had to anchor properly in order to pull the Frontier out
