i would first run my hand over the tire and feel for any seperation in the belts. most likely the cause. from my experience at around 7000 miles on the front tire and its starting to seperate and its time to replace it. i was running brigestone stock tire, michelin pilot power and sport, and shinko 003 on my 03 gsxr 1000 and i put 25,000 miles approx. on the bike in only two years, so i was riding the poop out of it