A pneumatic tire is provided which has sufficiently reduced rolling resistance during high-speed running and which has excellent durability. The pneumatic tire has a bead portion, carcass and tread, wherein: a bead-reinforcing layer that reinforces the bead portion from outside of the carcass is provided outside of the carcass in the tire axis direction; and the pneumatic tire satisfies (formula 1) and (formula 2) below, where Wt (mm) is the cross-sectional width of the tire when the tire installed on a standardized rim and the internal pressure is 250 kPa, Dt (mm) is the outer diameter, and the virtual volume V (mm.sup.3) is the volume of the space occupied by the tire.

1600≤(Dt.sup.2×π/4)/Wt≤2827.4  (formula 1)

[(V+1.5×10.sup.7)/Wt]≤2.88×10.sup.5  (formula 2)

Provided is a pneumatic tire having a sufficiently suppressed change in handling property and sufficiently improved durability. This pneumatic tire comprises a tread portion including a rubber layer, the rubber layer is formed of a rubber composition having 0.25 or less of a loss tangent (15° C. tanδ) measured under such conditions as 15° C., frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, the tread portion includes a plurality of rib-like land portions formed by circumferential grooves continuously extending in the circumferential direction, the tread portion has a ground contact surface partitioned, at the equatorial plane, such that one ground contact area Sa and the other ground contact area Sb satisfy a relationship of Sa>Sb, and (formula 1) and (formula 2) are satisfied where Wt (mm) is the cross sectional width of the tire, Dt (mm) is the outer diameter, and V (mm3) is a virtual volume being the volume of a space occupied by the tire when the tire is mounted on a standard rim and the internal pressure is 250 kPa.

1600≤(Dt.sup.2×ϕ/4)/Wt≤2827.4  (formula 1)

[(V+1.5×10.sup.7)/Wt]≤2.88×10.sup.5  (formula 2)

Provided is a pneumatic tire having a sufficiently suppressed change in handling property and sufficiently improved durability. This pneumatic tire comprises a tread portion including a rubber layer, the rubber layer is formed of a rubber composition having 0.25 or less of a loss tangent (15° C. tanδ) measured under such conditions as 15° C., frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, the tread portion includes a plurality of rib-like land portions formed by circumferential grooves continuously extending in the circumferential direction, the tread portion has a ground contact surface partitioned, at the equatorial plane, such that one ground contact area Sa and the other ground contact area Sb satisfy a relationship of Sa>Sb, and (formula 1) and (formula 2) are satisfied where Wt (mm) is the cross sectional width of the tire, Dt (mm) is the outer diameter, and V (mm3) is a virtual volume being the volume of a space occupied by the tire when the tire is mounted on a standard rim and the internal pressure is 250 kPa.

1600≤(Dt.sup.2×ϕ/4)/Wt≤2827.4  (formula 1)

[(V+1.5×10.sup.7)/Wt]≤2.88×10.sup.5  (formula 2)

A pneumatic tire comprises a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and tread rubber disposed on the outer side in the tire radial direction of the belt layer. The belt layer is formed by laminating a pair of cross belts having belt angles with an absolute value from 10° to 45° both inclusive and mutually opposite signs, and a circumferential reinforcing layer having a belt angle within a range of ±5° relative to the tire circumferential direction. The distance (Gcc) from the tread profile to the tire inner circumferential surface along the tire equatorial plane and the distance (Gsh) from the tread edge to the tire inner circumferential surface have a relationship satisfying 1.10≤Gsh/Gcc. The groove depth (Dsh) and under-groove gauge (UDsh) of the outermost circumferential main groove have a relationship satisfying 0.20≤UDsh/Dsh.

A pneumatic tire comprises a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and tread rubber disposed on the outer side in the tire radial direction of the belt layer. The belt layer is formed by laminating a pair of cross belts having belt angles with an absolute value from 10° to 45° both inclusive and mutually opposite signs, and a circumferential reinforcing layer having a belt angle within a range of ±5° relative to the tire circumferential direction. The distance (Gcc) from the tread profile to the tire inner circumferential surface along the tire equatorial plane and the distance (Gsh) from the tread edge to the tire inner circumferential surface have a relationship satisfying 1.10≤Gsh/Gcc. The groove depth (Dsh) and under-groove gauge (UDsh) of the outermost circumferential main groove have a relationship satisfying 0.20≤UDsh/Dsh.

A tire has a tire center in the tire width direction. An intersection point of a carcass outer surface with a parallel line extending parallel with a rotation axis and passing through a tire maximum width position is denoted as P1. An intersection point of the parallel line LP with a side surface is denoted as P2. An intersection point of the parallel line with a protrusion portion outer surface of a protrusion portion is denoted as P3. A distance between the tire center and the intersection point P1 is denoted as W1. A distance between the tire center and the intersection point P3 is denoted as W3. A distance between the intersection point P1 and the intersection point P2 is denoted as G1. A distance between the intersection point P2 and the intersection point P3 is denoted as G2. 0.80≤W1/W3≤0.95 and 0.1≤G1/G2≤1.

A tire has a tire center in the tire width direction. An intersection point of a carcass outer surface with a parallel line extending parallel with a rotation axis and passing through a tire maximum width position is denoted as P1. An intersection point of the parallel line LP with a side surface is denoted as P2. An intersection point of the parallel line with a protrusion portion outer surface of a protrusion portion is denoted as P3. A distance between the tire center and the intersection point P1 is denoted as W1. A distance between the tire center and the intersection point P3 is denoted as W3. A distance between the intersection point P1 and the intersection point P2 is denoted as G1. A distance between the intersection point P2 and the intersection point P3 is denoted as G2. 0.80≤W1/W3≤0.95 and 0.1≤G1/G2≤1.

A motorcycle tire pair includes a front tire 2 and a rear tire 42. A center arc index Ac, a middle arc index Am, and a shoulder arc index As are obtained based on a contour line TLf of a tread surface 16 of the front tire 2 and a contour line TLr of a tread surface 56 of the rear tire 42. In the tire pair, the middle arc index Am is greater than or equal to the center arc index Ac, and the shoulder arc index As is smaller than the center arc index Ac.

A motorcycle tire pair includes a front tire 2 and a rear tire 42. A center arc index Ac, a middle arc index Am, and a shoulder arc index As are obtained based on a contour line TLf of a tread surface 16 of the front tire 2 and a contour line TLr of a tread surface 56 of the rear tire 42. In the tire pair, the middle arc index Am is greater than or equal to the center arc index Ac, and the shoulder arc index As is smaller than the center arc index Ac.

Big wheel cars that have wheels with diameters of 24″, 26″, and 28″ have tires that are currently made specifically for various weather conditions which require the tires to have tread on the face of the tire, but nothing regarding high performance or racing applications. This invention will give the rear of the car more traction and safer stopping/steering performances during high performance applications that include DOT approved tires for public highways, and non-DOT approved tires for racing applications on raceways.