My Continentals are wearing fairly evenly, but are now probably in the last 10,000 km or so of their life. The tread is still well above the wear bars, but now by maybe only 2-3 mm. My question is this: I seem to have noticed a significant increase in impact noise, even on smooth pavement, and especially at slower speeds. It is almost like I am hearing every block of the tread plopping down. Am I nuts? Is this expected? Is it an indication of any breakdown in the tire structure or of creeping misalignment?