I find that I get the most even wear when I run my tires at 34-36 psi so I try to keep them at 34 year round. That's for on road. Off road is an entirely different story.

Different tires will 'feel' or react differently so you'll have to use trial and error to find what works best for you. Just make sure you keep it in the safe zone recommended by the mfr (I'd never run over 36 just for fear of breaking a bead).