MTB: I run the mud knobblies at 15 psi offroad- about 1/4 max-recommended, and the dry surface tyres at 75 per cent max. My offroad route is mostly stones in the dry and deep mud in the wet.

On the Dahon, the Marathons at as much as I can shove in with a hand pump, about 2/3rds of max. The CO2 pump when I use that gves about 60 psi, but that's too hard. I don't put more pressure in the rear than the front.