§ 159.3. Definitions.
The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise:
Bead—That part of the tire made of steel wires, wrapped or reinforced by ply cords, that is shaped to fit the rim.
Bead separation—A breakdown of bond between components in the bead area.
Bias ply tire—A pneumatic tire in which the ply cords that extend to the beads are laid at alternate angles substantially less than 90° to the centerline of the tread.
Carcass—The tire structure, except tread and sidewall rubber.
Chunking—The breaking away of pieces of the tread or sidewall.
Cord—The strands forming the plies in the tire.
Cord separation—Cords parting away from adjacent rubber compounds.
Cracking—Any parting within the tread, sidewall or innerliner of the tire extending to cord material.
Groove—The space between two adjacent tread ribs.
Innerliner—The layers forming the inside surface of a tubeless tire that contains the inflating medium within the tire.
Innerliner separation—The parting of the innerliner from cord material in the carcass.
Load rating—The maximum load a tire is rated to carry for a given inflation pressure.
Maximum load rating—The load rating at the maximum permissible inflation pressure for that tire.
Maximum permissible inflation pressure—The maximum cold inflation pressure to which a tire may be inflated.
Open splice—Any parting at any junction of tread, sidewall or innerliner that extends to cord material.
Overall width—The linear distance between the exteriors of the sidewalls of an inflated tire, including elevations due to labeling, decorations or protective bands or ribs.
Ply—A layer of rubber-coated parallel cords.
Ply separation—A parting of rubber compound between adjacent plies.
Pneumatic tire—A mechanical device made of rubber, chemicals, fabric and steel or other materials, which, when mounted on an automotive wheel, provides the traction and contains the gas or fluid that sustains the load.
Radial ply tire—A pneumatic tire in which the ply cords which extend to the beads are laid at substantially 90° to the centerline of the tread.
Rim—A metal support for a tire or a tire and tube assembly upon which the tire beads are seated.
Section width—The linear distance between the exteriors of the sidewalls of an inflated tire, excluding elevations due to labeling, decoration, or protective bands.
Sidewall—That portion of a tire between the tread and the bead.
Sidewall separation—The parting of the rubber compound from the cord material in the sidewall.
Size factor—The sum of the section width and the outer diameter of a tire determined on the test rim.
Test rim—With reference to a tire to be tested, any rim that is listed as appropriate for use with that tire in accordance with § 159.4(d) (relating to requirements). For purposes of this chapter and section 571.110, each rim listing shall include dimensional specifications and a diagram of the rim.
Tread—That portion of a tire that comes into contact with the road.
Tread rib—A tread section running circumferentially around a tire.
Tread separation—Pulling away of the tread from the tire carcass.
Cross References This section cited in 67 Pa. Code § 159.4 (relating to requirements).
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