Warranties can't be voided as a general rule.

If you are referring to warranty on problems that have no relation to the spacers, ie an engine or transmission problem, there is no issue.

If you have a vibration or tire wear problem and claim warranty, expect to get some pushback from the dealer who may point to the spacers as being a causal factor. Also, if the dealer has to take a wheel off to work on the vehicle as part of an unrelated warranty repair, they may take exception to remounting the spacer due to perceived liability issues.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue