When entering 26 into the wheel size setting on my Ultra 1000, I couldn't help but notice the huge difference in diameter between the rim and the outside of the mounted 26x4 tire. As I recall from the old days a typical 26x2 MB tire would ad somewhere between 3 and 4 inches to the rim diameter. The fatty looks like an add of 6-7 inches. should I measure the diameter or does the controller factor in a rubber amount and if so, how much?