Bought a new 2011 3.6R and immediately had shakes around 50-60. Tried road force balancing and rotating tires with no success. Finally worked with SOA and my dealer and had the shaker TSB done. 95% of the shake was gone after the TSB, but there still was a minor shake around 70. Lived with it and the original Continental tires for 87,000 miles. Finally needed new tires and switched to the Michelin Premier LTX tires. Have driven over 1,000 miles now on the new tires and the shake is gone. The vehicle also rides so much smoother than the Conti's. Just my experience with a shaker and what seemed to make the problem go away.