Currently, the number of elderly people is increasing in Japan. Among people with disabilities, the most common type is limb impairment. It is expected that the demand for wheelchairs will further rise in the future. In our previous research, a mechanism was developed to increase the radius of the wheels only when climbing stairs. To evaluate the performance of the developed wheels, experiments were conducted where stairs were pulled and climbed. However, since the pulling was done manually, the pulling force varied with each trial. In this study, an electric pulling device was created, and experiments were conducted to climb stairs with a constant pulling force. As a result, quantitative evaluation was possible by using a motor. It was also found that the contact position between the step and part of a wheel (named foot) affected the performance of the developed wheel to climb the stair.