To obtain a wheel control system by which a wheel is controlled by automatically detecting the wheel diameter of as many wheels as possible.

On the basis of the rotational speed ωn of a certain wheel and on the basis of the measured wheel diameter Ro and the rotational speed ωo of a specific wheel, a computing circuit 43 calculates a wheel diameter Rn by using Expression 2 so as to be outputted to monitor bodies 41. The monitor bodies 41 in respective vehicles 1 communicate with each other. A monitor body 41a in a vehicle having a wheel transmits the measured wheel diameter Ro and the rotational speed ωo to a vehicle having no wheel. Inversely, it receives the wheel diameter Rn of every wheel. It is not required to measure every wheel diameter, and an effect to automate the control of a wheel is obtained.