In this paper, steering characteristics of a rigid wheel (tire) on loose soil is investigated. Based on terra-mechanic analysis, the lateral force characteristics of a driving wheel is modeled as a function of slip ratio and slip angle. The model suggests that the lateral force decreases according to the increment of the slip ratio and increases according to the increment of the slip angle. Such characteristics are confirmed and evaluated by experiments using simulated lunar-surface soil, called Lunar Regolith Simulant. The proposed model is validated with the experimental results in reasonable precision. A model that properly predicts the lateral force will be useful for future practical issues, such as controlling the steering motion of a vehicle for following a desired trajectory in the operational phase, and also to compare the feasibility and/or stability of candidate steering maneuvers in the motion planning phase.