One of my 20" Eagle LS2s had 29 lbs of road force. My vibration is only felt in the floor and gas pedal. I didn't think that it was tires at first because usually high road force causes steering vibration. The new one I put on had 26. The rest are 15 and under. When I drove it home the vibration was almost gone. Surprised only 3 lbs. less made such a difference. I'm going to try another one tomorrow to get it under spec and see if it improves more. My Chevy dealer would not acknowledge the vibration. Said they drove it 8 miles. When I picked it up the odometer had 1 mile more than when I dropped it off after they had it for 3 weeks. Hmmmm