My 2017 C250d cabriolet is nearly one year old, and I have experienced very noisy tyres since new. They are run-flat. It is most noticeable at low speed e.g. 15-20mph, and when I brake and I'm coasting. It is difficult to explain the noise, but it is a low reverberating 'winding down' hum, which slows as the car slows. It sounds like the wheel is about to drop off! I've never experienced anything like it, and I hate it! I was recently told it is even noticeable from outside, so something is wrong. A friend has a new C63 Cabriolet and complained about her tyre noise, and MB admitted it is a known problem and changed them. But before I book in for my first service, has anyone else experienced noisy tyres like this?

 

I've never heard it being an issue to the point where a dealership has had to replace them, but run flat tires in general tend to be quite noisy because of their hard compound. Perhaps consider switching to a standard set when they need to be replaced.