tapping noise from osr at low speeds

[wilf1227]

Looking for any advice re the above.I have a 124 300e auto saloon. If you drive at speeds up to about 20mph with the window open you can hear what seems to be something tapping on or around the osr wheel.I have checked the pads and these seems ok just wondered if anyone else had come across this?

 

[Stratman]

Possibly a stone stuck in the tyre tread?

 

[wilf1227]

This has been going on for some time so I am sure it is not a stone. It does seem mechanical but is such a "light" noise it is impossible to replicate it on a ramp.