A very common reason of rattling wipers is inappropriate application of rain repellents. Avoid applying them if not really needed, but If it is required in your winter conditions, always use a quality product and precisely refer to manufacturer's instructions. Some products require application of a single layer, whereas others may require a second one and as a general rule completing the process in a coolish/shadow area to avoid fast evaporation/drying.
Scheibenwischer rattert
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A very common reason of rattling wipers is inappropriate application of rain repellents
Indisputable fact. If you never applied a rain repellent though and suffer from rattling wipers anyway, then the culprit might as well be a low-quality or worn-out wiper. Many of us use the "Bosch Aerotwin" wipers on their Beamers and I personally see them as a high-quality product. That would be my recommendation, if anyone asked ...
Greetz
Mike