BMW recommends 255/
50/19……make sure you’re not mixing up the aspect ration (the middle number) for the 18” & 19” tire sizes.
- 18 inch wheels are recommended to run 255/55/18
- 19 inch wheels are recommended to run 255/50/19
Again, check the info in your owners manual or the link to the part database site for the correct tire sizes. If you desire to select a different tire size that what is recommended….that could also be your choice as well as your consequence.