I have a 2011 Sport Activity with the 19" style 335 wheels. I drove models with 19s and 20s on two separate occasions; I liked the looks of the 20s more, but the ride was definitely better on the 19s. With the 19s and run flats, I find the ride very comfortable. I traded in a Lexus IS 350, and though the X5 definitely has more of a truck/SUV feel in the suspension, I find that I don't notice the small bumps/joints/road imperfections the way I did in the Lexus with 18" wheels and much less rubber sidewall. Another advantage of the 19s is getting all-season tires vs summer tires on the 20s, but that shouldn't be much of an issue for you in Texas.

All that being said, I think the 19s were a more practical choice, but I now find myself pricing 20s online....

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2011 xDrive 35i Sport Activity/Black Sapphire/Tobacco/Technology Pkg/Convenience Pkg/Premium Audio/Heated Rear Seats/Tint/Running Boards/Black Grill