Wow, that's interesting. The wheels I put on were only used for one set of tires, and sat in storage for over a decade. They didn't look any more corroded inside than any other used wheel, but who knows. Driving it again today, it doesn't seem like a perfectly rhythmic vibration, rather an irregular wobble, sort of like you described. What can be done if it's the wheel? How can you tell, via naked eye, if that's the issue? Would it be blatantly obvious? Nothing seems driveline-related as it's all dependent upon speed, not RPM or acceleration

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL