20" 214's vs. 19" 334's on '11 Xdrive 35i

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I have a 2011 Xrive 35i Premium on order, which comes with 19" Style 334 wheels (same width) all around. Bumping up to the Sport Activity model adds the 20" staggered 214's.

The X5 is going to be my wife's car, primarily, and I may use it from time to time on some slightly unimproved gravel/rocky roads. I was thinking about moving to the Sport Activity model, but can 214's handle these duties? My wife drove a Tahoe with 20' wheels for 3 years without a scratch, but I think the tires are even lower profile with the 214's.

Anyone care to weigh in with real-life off-road or wife's experience with 214's?