The recommended inflation on the factory placard is just the engineers trying to address the needs of the masses. Alternative tire pressures are okay, but diligent pressure monitoring is required. Always, always, always verify the maximum tire pressure on the sidewall of the tire to ensure that it exceeds the vehicle placard inflation. For example, I see too many people put P-Metric tires on a 3/4 or 1 ton truck. Most of these call for 80 psi in the rear tires on the placard, but the tire's maximum may be as low as 44 psi. I'm sure you can all see the potential dangers here. If you run under the recommendation pressure, be sure that you manually check tire pressures with a quality gauge at least once per week. I would also not run under 30 psi in any automobile/truck tire regardless of what the placard states. Also, if you cart any kind of load (including passegers), get the pressures back up to the spec on the vehicle placard. This is why placards are there . . . there are entirely too many "what-ifs", and the recommendation is a good compromise for a vast majority of end users.
1sttruck, I have always had to run 40 psi (as long as it does not exceed the tires' maximum pressure) for Tauri to wear their tires evenly. I have not really noticed any negative effects so long as the alignment is in spec.