This paper proposes an approach to evaluate the tractions of the vehicle wheels driven by DC motors directly. The database of the DC motors, such as current versus voltage, PWM and loading, has to be built through the automatic data acquisition system. Instead of the slip ratio measurements, the evaluation of the tractions can provide the force information of the traction wheels by using the interpolations of the database with applied voltages, PWM signals and measured currents of the DC motors. In order to verify the feasibility of this approach, the automatic data acquisition system has been implemented for a single traction wheel including the database establishments of DC motors. This system should assure that the commands and data transmitted are always correct. The details of the units in the system are discussed such as initializations of units, flow chart of PWM command transmissions, etc. The motor loadings are also evaluated with specific applied voltages, PWM values and measured currents. The result shows that it is feasible to evaluate the loadings through the interpolations of the database of the DC motor.