Two types of tire construction are common, cross-ply and radial ply.
The cross-ply tire is the older form. It is also called a bias-ply or conventional tire. It is constructed of 2 or more plies or layers of textile casing cords, positioned diagonally from bead to bead.
The rubber-encased cords run at an angle of between 30 and 38 degrees to the centerline, with each cord wrapped around the beads.
A latticed criss-crossed structure is formed, with alternate layers crossing over each other, and laid with the cord angles in opposite directions.
This provides a strong, stable casing, with relatively stiff sidewalls.
However, during cornering, stiff sidewalls can distort the tread and partially lift it off the road surface, and that reduces the friction between the road and the tire.
Stiff sidewalls can also make tires run at a high temperature. This is because, as the tire rotates, the cords in the plies flex over each other, causing friction and heat.
And a tire that overheats can wear prematurely.
