i dont know about the Z4, but on my audi i ran 22mm and 15mm spacers with no problems.
i raced the car at the drag strip, auto-x's, and drove it daily with no issues at all.
they are safe, i wouldnt worry about it.
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2011 BMW Z4 35i | FBO | VTT Stg 2+ (EK, 20T clipped)| Motiv PI| Motiv Tuned | Fuel-IT Stg 2 + inline fuel pump | Spec Stg 3+ clutch | MFactory flywheel | 606whp 575Lbs |
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