BMW WHEEL REFERENCE GUIDE
BMW Wheel Offset and ET Guide
ET is the wheel mounting-face offset in millimetres. The same ET value can produce a different inner and outer position when wheel width changes.
1. Read ET with wheel width
A move from 7J to 8.5J changes both edges of the wheel even when ET stays the same. Compare width and offset as one geometry problem.
2. Separate geometry from fitment
A calculator can estimate how far the inner and outer edges move. It cannot confirm brake clearance, tire shape, suspension clearance, body clearance, hardware, or legality.
3. Check front and rear rows
Staggered BMW applications may use different widths, offsets, tires, and part numbers by axle. Do not merge separate rows into one assumed specification.