The term 'Paving Substances' refers to materials used in the construction of roads, driveways, and other paved surfaces. TARS is a four-letter solution to this crossword and is an acronym for 'tar and asphalt road surfacing, ' which is a type of paving substance. Tar and asphalt are two of the most common materials used in road surfacing, and they are often combined to create a durable and long-lasting surface.