Bad tire? bubble in the tire? Or could be a bad bent rim.. Also if a tire sits flat for a while you will get what looks like a bump but it is a flat spot.. Tire is out of balance. Bad bearing you would have play when you grabbed it and moved in back n forth up and down. If you deflate tire and re inflate you may get rid of the wobble but like I said earlier if it sat flat for a while the tire could now be out of round..