I have a feeling you will have a lot of difficulty getting genuine BMW M3 wheels to fit on your 1er as the offsets will be too aggressive.
If you want 19's you'll probably have to go aftermarket. GTC and VMR's seem to have CSL replica wheels or similar for good prices and I think they come in 19s.
Or just go for some lightweight wheels from Apex or Forgestar.
For 8.5's at the front you will need a 45-48 offset and for the rear you will need 50 for 9's or 58 for 9.5's I think.
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