The control arms are what causes this odd tire wear. Easier to do the arms than replace the bushings; you'll get new ball joints in addition to just bushings if you replace whole arms. They're aluminium. You can handle this yourself, no spring compressor or other special tools beyond 13, 16, 18 mm wrenches, jack, and stands. Do all four upper arms, they should cost about $75 each. I think of this as a 75k maintenance item on Audis.

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1985 300TD
1984 380SL
1983 280SE (full Euro, trunk triangle and all!)

Formerly owned:
1986 420SEL
1984 300D
1983 300D
1981 300SD
1976 300D