Taildraggers (Including the P-47) naturally do better on the grass because of the distribution of the weight. Tricycle configurations tend to "dig" into soft surfaces, especially if weight is not kept off the NLG during taxi and rolling at high speeds (take off and landing). Most if not all tricycle landing gear configuations tend to shimmy at the NLG during higher speeds so many aircraft incorporate a "shimmy dampener" that tends to loose effectiveness overtime, especially when operating on dirt and grass surfaces.