I totally agree with you, but sometimes people don't have time to play around with the air pressure, so the factory pressure is just the guideline for people to follow. But there are so many different "I assume they are correct" pressures people put in their cars, and u think the BMW dealers or car mechanics should know about the tyre pressures, but sometimes you find they don't really know what's the "right" information to advice customers which I find it is very annoying.
