Effective Diameter (\( D_e \)):

\[ D_e = \frac{d}{\pi N} \]

Where:

• \( D_e \) is the effective diameter of the ground wheel under load, in meters (m).
• \( d \) is the distance for a given \( N \), in meters (m).
• \( N \) is the number of revolutions, in revolutions per minute (rpm).