I have a vibration on my 01 4L V6 4x4 Ranger at 40 and again at 60MPH that goes away when turning right at these speeds. I noticed this after changing brakes rotors and calipers. My Mechanic told me it was probably the tires (new tires same problem) he said front end was fine. while up on lift pasenger tire is harder to turn than driver side. I have driven almost 1500 miles in this condition. What could this be?