Tires ( Radial and Bias )

The bias ply tire construction utilizing rubber-coated layers known as plies composed of textile cords, usually nylon and sometimes Kevlar.  The plies layered diagonal from one bead to the other bead at about a 30 degree angle. One ply is set on a bias in one direction as succeeding plies are set alternately in opposing directions as they cross each other and the ends are wrapped around the bead wires, anchoring them to the rim of the wheel.  The layers of plies are them covered with more rubber to form the tread of the tire.  Bias ply tires are sometimes called cross-ply tires.

The radial is a type of tire that is constructed with rubber coated, reinforcing steel cable belts that are assembled parallel and run from side to side, bead to bead at an angle of 90 degrees to the circumferential centerline of the tire.   (As opposed to the 30 degree alternating application lengthwise as in bias ply tires).  This makes the tire more flexible which reduces rolling resistance to improve fuel economy.  Then numerous rubber coated steel belts are then constructed into the "crown" of the tire under the tread to form a strong stable two-stage unit.