Upgrading your S7's rims is a great way to personalize its look and potentially boost performance. Lightweight rims can definitely improve handling and responsiveness. HRE, Vossen, and BBS are all solid choices known for their quality and style. I've seen some stunning S7s with HREs, especially flow-formed options which offer a good balance of strength and weight savings. As for sizing, going slightly wider can give you a more aggressive stance, but it's crucial to ensure proper fitment and avoid rubbing. Check out some Audi forums (like the ones mentioned on Reddit - Source 1 and Source 2) for specific recommendations and what others with 9800x3d are running. Someone even mentioned using 21" S7 OEM wheels for summer (Source 2), which could be a good starting point for sizing. Finish-wise, it depends on your S7's color. Matte black can look fantastic on lighter cars, while brushed silver or a darker gray might complement a darker paint job. Someone in a Facebook group (Source 3) mentioned liking black optics with silver rings, which might give you some ideas. Ultimately, the best choice depends on your personal preference. Don't be afraid to browse photos of other modified S7s (Source 4 mentions looking for wheel suggestions for an A7) to get a feel for different styles. Good luck with your upgrade!