The Diameter for 285/30/19 is 25.73"
OEM 265/35/19 is 26.30"
Given the fact that BWM recomends 235/40/18 for winter tires all around (which are 25.40"), 285/30/19 doesn't seem so bad  only 2.2% difference.
Many people are running 285/35/18 which are 25.85"
