All suspension components were checked by BMW...and my car only has 12,000 miles on it and it's not rough miles either. And that it ran with no vibration with the 19's on it.

I think you are right that it should be able to take the 20's with no problem.

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2007 328i Sport, Monaco Blue
2011 X35D - sold -Space Grey
2004 X5 4.4i - sold - Kalahari Beige
2001 X5 3.0i - sold - Pearl Beige
2006 325i Sport, Sonora Beige
2000 323i - sold - Sienna Red