[GTP Dad]

A lot of components could cause this problem but the symptoms you describe are related to the brakes. If you felt a shimmy or vibration while driving I would suspect the suspension has a problem but given the fact that the problem only occurs while under braking I would believe that the problem is due to a warped rotor. Once you either have it turned or replaced I would suspect the problem would go away. By the way the tires could cause this problem but you would probably see uneven wear or have very little tread left on the tire. Let me know how it behaves after the rotors are changed.