Mystic noise iside a rim?

[Werner]

Guten Abend.

I found something very strange noise on a rim that I can't explain. When I turn the wheel, I can hear a sound as if sand were falling inside.

First I pulled the brake drum off because I thought there was something loose there.

No, the noise comes from the wheel. I removed the tire and I can still hear the trickling noise. It seems to come from the side of the rim. Inexplicable that something could trickle in it. I think that's all full metal.

Does anyone have any idea about this mysterious curiosity?