You are talking about negative camber. That puts more weight on the insides of the tires which promotes heat and causes premature wear. This additional wear isn't nearly as much as most folks think it is. A couple degrees of negative camber with zero toe (tires pointed straight ahead) isn't bad at all. Add in a half degree of toe and the wear accelerates quite a bit because now the portion of the tires bearing all the weight aren't just rolling along in concert, they are somewhat opposed to each other. This both creates additional heat and scrapes the rubber right off of both tires.
This is negative camber on my car before a track day. Note that I have toe set at zero and have had no tire wear issue whatsoever. During autocross season I would wear the outsides first even with about 2 degrees of negative camber.
You can take a tire off and examine the tread for clues as to why it is wearing prematurely. Tires generally show signs of feathering or other damage from improper settings. Bear in mind that Audi's recommended settings are quite wide and are for cars at stock ride height on all season tires rated for 60k miles or so. A soft sport tire on a lowered car is an entirely different matter.
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