My dad has been feeling a reoccuring vibration, when driving over 60mph on concrete, in the steering wheel. When he is driving on asphalt, there are no issues. I should state that the wheels have been balanced in the past week and a half, the tires are four months old, the entire suspension and steering systems have been replaced-including both axles. I am going to take the car back in to check the wheel balance, but absent that I am at a loss. I should mention the car has Bilstein HDs, TME sport springs, as well as Voxx MG 17" wheels, and Michelin 215/45/17 tires. Any thoughts would be greatly appreciated. Thanks!