Smuggling noise back right :-((

Good morning together!
I have a problem since yesterday, which is as follows:
==References== 40 km/h comes from the rear right such a funny noise, it seems to come out of the brake. It sounds like a little stone that you shake in a coffee can, honestly!
From 50 km/h nothing can be heard, only when I slow down to step speed, clapping-di-klack-klack..........is probably due to the diminishing centrifugal forces.
I have to say that the night before yesterday I drove along a gravel road (grain size 5mm to 1cm). What's that? Can such a stone get stuck somewhere?
Had already the rim off, but nothing can be seen. Wants to have tires and rims registered for Tüv today, but what does that look like when I start with such funny noises, they're sending me back home, right?

Help!

Greetings, Matthias