X3 is xdrive right? So, maybe it was staggered, too? I don't know what they did, but I put Michelin PS4S staggered 225/40r18 and 255/35r18 which is 4% less diameter, and it still rides better than Pirelli P7 run flats. My run flats weren't even that bad, but by time worn at 5 years the rears were slipping on take off. I never get traction control to go off anymore on street.
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