To simultaneously achieve the acquisition of operational stability, the suppression of the increase of noise after use, and the suppression of the deterioration of the comfortable riding after use.
Although the volume of a bead filler 22 is reduced compared with a conventional volume by setting the height BH of the bead filler 22 within the range from 20% to 35% of the height SH in the cross section of a tire, the reduction in the stiffness due to a reduction in the volume of the bead filler 22 is supplemented by a reinforcing layer 44. Therefore, the operational stability is secured. Although the hardness of the bead filler 22 increases further with the use of the tire, the volume of the bead filler 22 is small compared with the conventional. Therefore, the degree of the noise and the deterioration of the comfortable riding can be reduced even if the hardness of the bead filler 22 is increased. The hardening of the reinforcing layer 44 due to its degradation has a small effect on the noise and comfortable riding because the reinforcing layer 44 is thin compared with the bead filler 22 and has a small effect on its bending stiffness. Therefore, the operational stability, the noise, and the comfortable riding are maintained in a well balanced state from an initial stage to a middle stage and after that. Therefore, the acquisition of operational stability, the suppression of the increase of noise after use, and the suppression of the deterioration of comfortable riding after use can be simultaneously achieved.
Kato Kazunori
Katsuichi Nishimoto
Hiroshi Fukuda