RADIAL TIRES

The body ply cords are placed straight across the tire from bead to bead. In addition, radial tires have belt plies which run circumferentially around the tires, under the tread. They constrict the radial ply cords and stabilize the tread area.

BIAS TIRES

Have multiple layers of plies with the cords in adjacent plies running in alternate diagonal directions from bead to bead. The tires may also have narrow plies under the tread, called breakers, with cords that lie in approximately the same direction as t he body ply cords.

The type of construction can be determined by looking at the size designation molded on the tire’s sidewall. Conventional radial truck tire sizes have an “R” in the size designation, rather than the hyphen. For example a 10.00R20 tire is a radial, while the 10.00-20 tire is a non-radial.

In addition, radial tires have the word “RADIAL” molded onto the sidewall. Metric radial truck tires also use an “R” in the size designation, e.g., 285/75R24.5.