ABSTRACT
Tires are essential for effective operation of most forms of transportation, ranging from passenger automobiles to heavy-duty trucks, farming vehicles, and aircraft. The pneumatic tire is not only the most complex composite product in mass production but also the most complex component on a vehicle. It consists of a variety of materials such as natural rubber (NR), synthetic elastomers such as styrene butadiene rubber (SBR) copolymers, and a wide variety of chemicals; textiles such as nylon and polyester; and a range of brass-and bronze-coated steel wires. Over the last 30 years, tires have undergone a major evolution. In the 1950s, tires were predominantly of a bias ply construction and required the use of an inner tube for air retention. Bias or diagonal ply tires describe a tire construction where the ply cords extend to the beads and where the ply cords are laid at an angle between 36° for passenger tires and 42° for heavy-duty large truck tires (Figure 14.1). Automobile tires lasted for between 15,000 and 25,000 miles, after which they were replaced. Though the use of bias tires in many markets has now been virtually eliminated, they still have a very large market share in Asia wherein some severe applications can outperform radial constructions.
