That should not be a concern at all... You put in the type of bimmer you have and the web site establishes the type of wheel that is specifically designed to fit your car. There is a distinct difference between 3's, 5's, 6's and 7's. Each bimmer has a unique size. The following is for a 3 series bimmer. Make sure you order the correct wheel size.
Reading Wheel Sizes:
Example Size: 15x7 4-100 40S
15 - Rim diameter in inches.
7 - Width of rim in inches.
4-100 - Bolt Pattern.
4 - Number of lug holes in wheel.
100 - Distance between lug holes (in millimeters).
Some wheels have multiple bolt patterns.
15x7 4-100/108
This wheel fits cars with both 4-100 bolt patterns and 4-108 bolt patterns.
40S - Offset and finish
40 - Measures in millimeters how far back or forward the mounting surface (face) is from the center of the wheel.
S - Silver Finish.
There are many different finish designations.
Happy Motoring...[driving2]