knocking noise

[nobblebonce]

when im driving along i can hear a knocking noise coming from the rear, it sound like, when you go over the lines in the road that they place just after a spped camera, and when i slow down the noise dies down.

what could this be, im thinking ball joint or bearing

how much am i looking at to get this repaired.

 

[nickl360]

A bearing normally makes a humming noise so I doubt it will be that.

 

[FeelX]

Is there something stuck in the tyre? Could be a screw or stone stuck in the profile that might make a tapping noise.