When driving about 60 - 70 mph and the radio is turned off I notice a low sound coming from the rear. Sound's like a continuous subwoofer activity. It's only above 60 mph and disappears at 70 mph (maybe the wind noise is louder).
No difference whether wing is up or down. Also different tarmac has no influence.

Anybody else noticed it?

I have stock rims, pilots, not lowered (yet!).

Thanks and greets.