I've called three independent BMW tuners in town and also written feedback from BavAuto that a staggered setup on original "square" is fine as long as the diameter/circumference is the same, back to front...which is basically what all of you are saying. What irritates me is that the folks at the dealership told me that the factory staggered setup was "specially tuned." to accommodate the staggered configuration. I'd they really know or their making stuff up.

 

Stock Sport Staggard is

19x8.5 ET 35 - 245/35/19
19x9.5 ET 45 - 275/30/19

I am running 245/40/19 & 275/35/19