Ethan

Measure from the centre of the hub to the bottomlip of the rear fender on both sides & compare.
I doubt the spring is causing the noise.
Your spring pad ( cushion where the spring sits at the top ) possibly.
It would also be worth getting a friend to bounce the rear up & down, while you watch/listen from under the car.
You could spray some lubricant at the suspected area (s ) & isolate the source of the noise.

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2007 C 230 Sport.