Today I did some high speed runs, between 85-90 MPH, sixth gear, and noticed more than usual engine vibration in that speed range. My bike has ~ 25k miles and I was wondering if it could be front tires, shocks, etc. The tires are Michelin PR2, from mid 2009 and seem to be still in good shape. However, there is some cupping in the front; the rear looks very good. Still running the original shocks.