SurfaceMap tells GroundDetection which SurfacePreset to use for which terrain texture and/or object tag.GroundDetection runs a check for each WheelComponent to determine which surface that WheelComponent is on. This is done by checking all the assigned SurfaceMaps in order and if any SurfaceMap has a matching terrain texture index in Terrain Texture Indices list, or the object the wheel is on has the tag from Tags list, Surface Preset will be assigned to that WheelComponent.
Adding a gravel SurfaceMap will be used as an example.
SurfaceMap by clicking on + button on the bottom of the list.Terrain Texture Indices list.GravelRoad) to those objects and add it to Tags list.