I run 4-6 psi depending on the coarse...Oh wait that's the Trials bike...
12-14 front and back. Never spun a tube yet. Makes ya cringe a bit hitting a big rock a higher speeds but I haven't had a front flat for some years either.
tire pressure is just like suspension settings its adjusted to change how the bike handles that being said start with 12 and adjust up or down as needed for your bike, riding style and conditions.