Loki,

Nothing wrong with the 20" setup as a daily driver. Problem is the OEM runflats might last 12-15K miles, and it will run you $1,500+ for a new set. You might factor that in to your decision. Yeah, summer tires might grip a little better, but anyone who really cares about handling isn't driving a 5500 lb SUV.

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2008 X5 4.8i, Jet Black, Tobacco Nevada leather & just about everything else (no vent. seats, no 3rd row)