I just look in my owner's manual and it's indicate how to see the wheel size on the speedometer, but I didn't found something about changing the wheels size. I have a set of 19/17 and the stock wheels 21/18 and really wish I can change it. I saw that it is possible on a 950 and on the regular 990. I saw some instruction on threads saying: Turn key on Press Mode until the F display comes on Press and hold both the Mode and Set buttons for ~ 10 seconds. The current wheel size will appear on the display Press Mode and it will toggle between 21, 19 Select 19 Press the set button. But on the R, the Mode button switch between ODO, Trip1, Trip2, Temp... can't display the F Mode.... Any idea?