Generally, wheel mechanisms are inferior to a tracked or walking mechanism in terms of step climbability or traversability in rough terrain; however, they are superior in terms of energy efficiency, structural simplicity, and carrying capacity. This paper proposes a new wheel mechanism, the swing-grouser wheel, which can climb high steps (especially in low friction environments) and has high energy efficiency. In addition, the swing-grouser wheel can climb regardless of the body inclination. Its merits are compared to the results of prior studies. Furthermore, the performance of the swing-grouser wheel was confirmed using a real device experiment and a 2D physics simulation, and improved using a full search of the parameters of the swing-grouser wheel. As a result, one improved parameter resulted in climbing at over 68% of the wheel diameter in a low friction environment; additionally, the energy efficiency was better than that of the previous model.