Spare tires provide crucial backup out on the open road. Unfortunately, new BMWs do not have spare tires. Instead, BMW outfits their cars with run-flat tires. When punctured, run-flat tires can be safely driven on long enough to reach your home or an auto repair shop.
Ditching the spare tire provides BMW with a few advantages. It makes their cars slightly lighter and more fuel efficient. Passing the cost of spare tires onto their customers also saves their company money.