I think you might have a mistake very minor though
you calculated Sidewall height to be 3.897
Sidewall Height (SH):
SH = 7.0866" X 0.55 = 3.897"
but in your formula you used 3.189. Using 3.189 should have gotten a tire diameter of 23.378 but you got the tire diameter using 3.897 which gives you a diameter of 24.8 like you calculated
Tire Diameter in Inches:
SH + SH + WD = Tire Diameter
3.189" + 3.189" + 17" = 24.8"
Oppsee - - busted a month later. . . :spank:
Kudos for catching that! :thumbup: