Happy to help! For a 17" wheels on your 1 series, we would recommend going with our 17x8.5" ET40 paired with 235/40-17 tires. Depending on your ride height, and tire brand/compound, a touch of negative camber may be necessary. 245/40-17 tires can fit as well, but will require approximately -1.5 degrees or more of front camber. Rear rolled fenders and/or rear negative camber may also be required.
You can also run a 17x9" ET42, but that is quite an aggressive fitment and will require heavier modifications. Most individuals running this setup are looking to maximize their sidewall support when running 245/40-17 tires. This setup may require a spacer up front depending on what suspension you have and along with negative front camber. The rear will be very aggressive, requiring a heavy fender roll and negative rear camber. The E90 hub conversion is a great option to gain clearance in the rear however.
We would recommend going with the 17x8.5" ET40 if you're looking for the easiest fit. Check out the photo below of a 1 series race car running the 17x8.5" ET40 fitment all around.
-Matt
