I to have Pirelli MT66 on mine, just put them on about a month ago but so far they are nice.
I found the artlicle on air pressure:
In summary, take the air pressure cold. Ride for about 15 minutes at highway speeds and check the pressure again. If it goes up 3 psi, you're good. If it goes up more than 3 PSI, your intitial pressure is too low. If it does not go up 3 psi, then your initial pressure is too high. The 3 psi number is to allow the tire to warm up correctly.
I suppose you could chase your pressure around forever based on the temperature when you start, however it is at least one good way to attempt to arrive at a pressure if you don't agree with the manufacturers.