The data of draft (D) and wheel slip (S) indicated a direct relationship between them, i.e., the wheel slip increases with the increase in draft of the tractor under different gear settings both at rated speed (i.e., 2000 rpm) and three-fourth rated speed (i.e., 1500 rpm) with pneumatic wheels as well as steel wheels. The general form of the empirical equation developed to relate draft and wheel slip is an Exponential Association of Growth Model and is given below: