# LCA as a Tool for the Environmental Management of Car Tire Manufacturing
## 2 Life Cycle of a Car Tires
### The Production Stage
With the top product quality in mind, all materials should be carefully selected on the basis of their respective physical and chemical properties, size, thickness, cutting angles, etc. Design specifications must be observed at every production plant, regardless of its location, thus ensuring that the same tire types provide the same performance, regardless of the place of manufacture [10]. The structure of rubber compounds is carefully adjusted to impart desired properties to the tire, so as to ensure its proper functioning and so that it will serve its intended purpose, e.g., a different compound is used in a summer versus winter tire. Moreover, rubber compounds of specially engineered properties build different parts of the tire, such as the sidewalls, the inner liner, or fillers in the bead zone, all of which are made of various types of rubber compounds. The compounds typically include the following materials: synthetic rubbers (butyl, SBR, BR), natural rubbers, oils, fillers (silica, soot), Sulphur, resins, anti-aging agents (antioxidants), vulcanization accelerators, and other agents as per specific requirements. The approximate material consumption involved in producing 1000 kg of tread rubber compound for a passenger car tire is 500 kg of rubber (mainly synthetic), 150 kg of silica, 150 kg of carbon black, 20 kg of Sulphur, 20 kg of resin, 100 kg of oils, and about 60 kg of other components [12; 13]. All the ingredients are machine-mixed, their quantity and the adding sequence being crucial, until a homogeneous mass is obtained. The prepared compound is formed into plates or ribbons, whose dimensions facilitate their use in the subsequent stages of production. The compound surface is next coated with a release agent, for easier separation of rubber layers in the later stages, and the rubber compound material itself is subjected to accuracy measurements and analyses to verify its compliance with the design specifications [14]. An integral part of the tire design are the steel and textile cords. They form a carcass of the tire, which guarantees its required stiffness and shape, and which translates into a desired level of performance while driving. A single thread of a textile cord is made of twisted weaves of a large number of ultra-thin viscose, nylon, aramid, and polyester fibers (a single 195/65 R15 tire contains between 1500 and 1800 threads) [15]. The purpose of bead wires is to enable mounting a tire on a rim. There are several technologies for their production. They may come in the form of rings formed by braiding several wires with a round cross-section or by winding several layers of tape. The beads consist of separate wires of a rectangular or polygonal cross-section, coated in a rubber compound. Having all the components collected and prepared in advance, the confection stage may commence. The tire building process consists of arranging the pre-products in a strictly controlled sequence. Depending on the technology, a raw tire is obtained in a one- or two-stage process, which is followed by vulcanization in special molds, and then quality control [16; 17]. The flowchart in Figure 1 presents the car tire production process. As mentioned, the technologies used by tire manufacturers involve one or two stages. In the former case, the entire tire is produced on a single machine; in the latter, the carcass is typically put together in the first stage, and the basic and supplementary layers and technologies (belt, tread, etc.) are fitted consecutively [17]. The layers of the tire are laid flat inside a drum, which is next filled with air, the pressure of which causes the layers to bond. In the next stage, the structure is subjected to rolling, which shapes the tire, ensures the strong bonding of components and guarantees the removal  
Figure 1: The tire-manufacturing process flowchart. of excess air that could become trapped between the components. The process output is the raw tire, which undergoes dimensional and shape control tests for errors [15].