The Off-road type is meant for paths that are impossible to drive with a regular car. Useful for mud roads, cart tracks, or roads with large holes that are only suitable for 4x4, in case they need to be displayed. If not necessary, better leave them out. Currently, Waze does not plan to support a 4X4 vehicle type in the client, but the developers have left this option for editors to map these paths, so they can be displayed on the map.