I just replaced my PR4s with another set of PR4s. I got ~16k miles out of them!
What happened with your tires?yup! it's a fact, less air will form more contact patch with the tarmac. but be careful, under inflation will induce uneven treadwear depending on size, shapes and angles of the tread pattern. I have had an unpleasant experience with Michelin Pilot Street Radial, front and rear.