FSETH true true but I plan on some winter snow driving, it has started snowing here in the mountains, so summer alloys/tires off and will get some taller tires with smaller rim, you are right the difference between the current rear 285/45 r19" (diameter 73.91cm) and 235/65 17" (diameter 73.73cm) is minimal but according to the url kindly added it means when the speedometer reads 100km per hour I am on doing 96 in reality, hmmm