Sakura knobbies front and rear all year.
Trials on the rear. I swap from a knobbie on the front depending on
where I plan to ride. Moab, Utah, slick rock. Trials on the front too.
My present tire combo is a Dunlop 739F on the front and a Dunlop
D803 on the rear. I have run the IRC trials tires in the past and like
them very much.
Jeff
I can't get over how good the trials tire is. Stock, gasgas makes the best bush bike (IMHO), but now it's even better. Believe the hype about trials tires, and rekluse clutches.
Mitas ET-01 rear trials....UNREAL so far, just stunning. Will only go back to a knobby in super muddy or sandy conditions.
Skidad
Before you do that try lowering your tire pressure to about 5 to 7 psi and try it in the mud and sand. I expect that you will be pleasantly surprised.