4668-1. Specifications
RimA metal support for a tire or a tire and tube assem-
bly upon which the tire beads are seated
Rim diameter (Wheel diameter)Nominal diameter of the bead seat
Rim size designationRim diameter and width
Rim type designationThe industry manufacturer’s designation for a rim
by style or code
Rim widthNominal distance between rim flanges
Vehicle capacity weight (Total load
capacity)The rated cargo and luggage load plus 150 lb. (68
kg) times the vehicle’s designated seating capacity
Vehicle maximum load on the tire
The load on an individual tire that is determined by
distributing to each axle its share of the maximum
loaded vehicle weight, and dividing by two
Vehicle normal load on the tire
The load on an individual ti re that is determined by
distributing to each axle its share of curb weight,
accessory weight, and normal occupant weight
(distributed in accor dance with Table 1
* below), and
dividing by two
Weather sideThe surface area of the rim not covered by the
inflated tire
Bead
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 separationA breakdown of the bond between components in
the bead
Bias ply tire
A pneumatic tire in which the ply cords that extend
to the beads are laid at alternate angles substan-
tially less than 90 degrees to the centerline of the
tread
CarcassThe tire structure, except tread and sidewall rubber
which, when inflated, bears the load
ChunkingThe breaking away of pieces of the tread or sidewall
CordThe strands forming the plies in the tire
Cord separationThe parting of cords from adjacent rubber com-
pounds
Tire related termMeaning
4688-1. Specifications
Outer diameterThe overall diameter of an inflated new tire
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
Passenger car tire
A tire intended for use on passenger cars, multipur-
pose passenger vehicles, and trucks, that have a
gross vehicle weight rating (GVWR) of 10,000 lb.
or less.
PlyA layer of rubber-c oated parallel cords
Ply separationA parting of rubber compound between adjacent
plies
Pneumatic tire
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
A pneumatic tire in which the ply cords that extend
to the beads are laid at su bstantially 90 degrees to
the centerline of the tread
Reinforced tire
A tire designed to operat e at higher loads and at
higher inflation pressures than the corresponding
standard tire
Section width
The linear distance between the exteriors of the
sidewalls of an inflated tire, excluding elevations
due to labeling, decoration, or protective bands
SidewallThat portion of a tire between the tread and bead
Sidewall separationThe parting of the rubber compound from the cord
material in the sidewall
Snow tire
A tire that attains a traction index equal to or
greater than 110, compared to the ASTM E-1136
Standard Referenc e Test Tire, when using the snow
traction test as described in ASTM F-1805-00,
Standard Test Method fo r Single Wheel Driving
Traction in a Straight Line on Snow-and Ice-Cov-
ered Surfaces, and which is marked with an Alpine
Symbol ( ) on at least one sidewall
Tire related termMeaning
