Bead means the part of the tire that is made of steel wires, wrapped or reinforced by ply cords and that is shaped to fit the rim.
Bead separation means a breakdown of the bond between components in the bead.
Bias ply tire means a pneumatic tire in which the ply cords that extend to the beads are laid at alternate angles substantially less than 90 degrees to the centerline of the tread.
Carcass means the tire structure, except tread and sidewall rubber which, when inflated, bears the load.
Chunking means the breaking away of pieces of the tread or sidewall.
Cord means the strands forming the plies in the tire.
Cord separation means the parting of cords from adjacent rubber compounds.
Cracking means any parting within the tread, sidewall, or inner liner of the tire extending to cord material.
Extra load tire means a tire designed to operate at higher loads and higher inflation pressure than the corresponding standard tire.
Groove means the space between two adjacent tread ribs.
Innerliner means the layer(s) forming the inside surface of a tubeless tire that contains the inflating medium within the tire.
Innerliner separation means the parting of the innerliner from cord material in the carcass.
Light truck (LT) tire means a tire designated by its manufacturer as primarily intended for use on lightweight trucks or multipurpose passenger vehicles.
Load rating means the maximum load that a tire is rated to carry for a given inflation pressure.
Maximum load rating means the load rating for a tire at the maximum permissible inflation pressure for that tire.
Maximum permissible inflation pressure means the maximum cold inflation pressure to which a tire may be inflated.
Measuring rim means the rim on which a tire is fitted for physical dimension requirements.
Open splice means any parting at any junction of tread, sidewall, or innerliner that extends to cord material.
Outer diameter means the overall diameter of an inflated new tire.
Overall width means the linear distance between the exteriors of the sidewalls of an inflated tire, including elevations due to labeling, decorations, or protective bands or ribs.
Passenger car tire means a tire intended for use on passenger cars, multipurpose passenger vehicles, and trucks, that have a gross vehicle weight rating (GVWR) of 10,000 pounds or less.
Ply means a layer of rubber-coated parallel cords.
Ply separation means a parting of rubber compound between adjacent plies.
Pneumatic tire means a mechanical device made of rubber, chemicals, fabric and steel or other materials, that, when mounted on an automotive wheel, provides the traction and contains the gas or fluid that sustains the load.
Radial ply tire means a pneumatic tire in which the ply cords that extend to the beads are laid at substantially 90 degrees to the centerline of the tread.
Reinforced tire means a tire designed to operate at higher loads and at higher inflation pressures than the corresponding standard tire.
Rim means a metal support for a tire or a tire and tube assembly upon which the tire beads are seated.
Section width means the linear distance between the exteriors of the sidewalls of an inflated tire, excluding elevations due to labeling, decoration, or protective bands.
Sidewall means that portion of a tire between the tread and bead.
Sidewall separation means the parting of the rubber compound from the cord material in the sidewall.
Snow tire means a tire that attains a traction index equal to or greater than 112, compared to the ASTM F2493 standard reference test tire when using the snow traction test on the medium pack snow surface as described in ASTM F1805-20 (incorporated by reference, see § 571.5 ), and that is marked with an Alpine Symbol specified in S5.5(i) on at least one sidewall.
Test rim means the rim on which a tire is fitted for testing, and may be any rim listed as appropriate for use with that tire.
Tread means that portion of a tire that comes into contact with the road.
Tread rib means a tread section running circumferentially around a tire.
Tread separation means pulling away of the tread from the tire carcass.
Treadwear indicators (TWI) means the projections within the principal grooves designed to give a visual indication of the degrees of wear of the tread.
Wheel-holding fixture means the fixture used to hold the wheel and tire assembly securely during testing.
Inflation pressure (kPa) | |
Standard | Reinforced |
180 | 220 |
Tire application | Test pressure (kPa) |
Passenger car tires: | |
Standard load | 220 |
Extra load | 260 |
Light truck tires with a nominal cross section [LESS THAN EQUAL TO]295 mm (11.5 inches): | |
Load Range C | 320 |
Load Range D | 410 |
Load Range E | 500 |
Light truck tires with a nominal cross section [GREATER THAN]295 mm (11.5 inches) | |
Load Range C | 230 |
Load Range D | 320 |
Load Range E | 410 |
Tire application | Test pressure (kPa) |
Passenger car tires: | |
Standard load | 180 |
Extra load | 220 |
Light truck tires with a nominal cross section [LESS THAN EQUAL TO]295 mm (11.5 inches) | |
Load Range C | 260 |
Load Range D | 340 |
Load Range E | 410 |
Light truck tires with a nominal cross section [GREATER THAN]295 mm (11.5 inches) | |
Load Range C | 190 |
Load Range D | 260 |
Load Range E | 340 |
Test period | Duration (hours) | Load as a percentage of tire maximum load rating |
1 | 4 | 85 |
2 | 6 | 90 |
3 | 24 | 100 |
Tire application | Test pressure (kPa) |
Passenger car tires | |
Standard load | 140 |
Extra load | 160 |
Light truck tires with a nominal cross section [LESS THAN EQUAL TO]295 mm (11.5 inches) | |
Load Range C | 200 |
Load Range D | 260 |
Load Range E | 320 |
Light truck tires with a nominal cross section [GREATER THAN]295 mm (11.5 inches) | |
Load Range C | 150 |
Load Range D | 200 |
Load Range E | 260 |
Load Range C | 260 kPa. |
Load Range D | 340 kPa. |
Load Range E | 410 kPa. |
For light truck tires with a nominal cross section greater than 295 mm (11.5 inches), the maximum permissible inflation pressure to be used for the bead unseating test is as follows:
Load Range C | 190 kPa. |
Load Range D | 260 kPa. |
Load Range E | 340 kPa. |
49 C.F.R. §571.139