hello i have a xb12's 07 for about two years. last week i install new tires Metzler M5+ balancing the wheels. when i drive more then 70 MPH the bike start to shake aggressivly it's tail. i replace the whell bearings and lub the axel like the service book says. but still nothing has changed. these tail's shaking happend to me before and when i replace the bearings they simply gone for couple of mounth but still it came again and now i dont know what to do and why is this occurs. waiting for your answers ! thanks Ohad from ISRAEL.