I have been getting an odd noise, like something is on the rear tire that rubs every time it goes around. I've put it up on the rear stand and looked at the tire and brake disc, but can't find anything obvious. I'm not 100% sure it's the tire, but it's occurring at about the right frequency, and slows as the bike slows (in neutral, regardless of engine speed). Any ideas where to look? ('08 CBR600RR) I can't hear it when I rotate the rear tire on the stand, and I don't have a front stand, but couldn't find anything obvious on the front tire or brake discs, either.