I´ve just ordered my X5/4.4 here in Germany.But I´m not sure to take the SportPackage. The 17"-tires are for "all seasons" and BMW say´s, that it´s better to use special M+S-tires in the winter instead of the 19" from the SP. Has anybody made experiences driving the 19" in the snow and on streets covered with ice? Is driving with SP remarkable less comfortable,smooth and quite? Thanks for your opinions from Berlin!