1. Keep your OE style 334's (as back up or as extra set). You might just get tired of style 214's ...
2. Get style 214, either OE used or aftermarket. Depending on how much of a purist you are, style 214 20-inch aftermarket run about $200/ea, staggered or non staggered. If you go non-staggered, you won't need the fender flares and you can buy one size tire that you can now rotate. See 4. If you do get staggered, I highly recommend the flares because you won't like the look.
3. Get 4 TMPS from
BavarianX (BERU brand, OE supplier to BMW).
4. Get 4 non-RFT tires. Consider size 275/45x20 tires ... Make SURE you read the specifications on the tires, e.g the manufacturer's recommended max wheel width that the tire can be mounted on. This size tire is slightly taller than the size(s) BMW recommends for staggered wheels and will give only a 2.5% speedometer error. Acceptable in most cases. Plus you have a much wider variety of brands to choose from (lower prices). If you go staggered with a 10.5 wide wheel, you can still use size a size 275/45x20 tire, just pick a brand that allows you to "stretch" it.
5. Have everything mounted and balanced at a competent shop, using a
Hunter GPS 9700