Hello, I have read that the rim or tyre size affects the wheel diameter and thus the ground clearance of the car. I do not know how to calculate this. So e.g.: 235/55 R18 means Q = 235 = tyre cross-section in mm V = 55 = ratio tyre height to tyre width in % Z = 18 = 18 inches diameter (equivalent to x 2.54 = 45.72 cm) From these values one must now be able to determine the diameter or the half-meter in order to compare how much higher or more lower a car stands on the road if it uses this or that tire size. That is certainly quite easy to determine if you know it. Does anyone know it ? Thanks rapper PS: I tried the following formula – true the ? diameter = (Q*V/100)*2) + (Z*2.54)*10) With this formula I would get with the above mentioned tires / rim size 235/55 R 18 to a diameter of 715,7 mm With a tyre / rim size of 205/60 R16 I would get to diameter = 652,4 mm