Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1999-06-30
2001-08-14
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S552000, C152S554000, C152S557000, C152S559000
Reexamination Certificate
active
06273164
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pneumatic tire for motorcycles, more particularly to an improved carcass structure capable of improving tire rigidity during cornering and ride comfort during straight running.
As the motorcycles bank during cornering, it is important that motorcycle tires can display a proper rigidity during cornering to keep a stable bank angle. If the carcass rigidity is increased in order to obtain the necessary tire rigidity, shock absorption and ride comfort during straight running become worse and further the tire weight increases. If the carcass rigidity is decreased in order to improve the shock absorbing performance, cornering becomes unstable. Thus, the rigidity during cornering and shock absorption or ride comfort during straight running are antinomy.
It is therefore an object of the present invention to provide a motorcycle tire in which both the rigidity during cornering and ride comfort during straight running can be improved.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a motorcycle tire comprises a carcass composed of a low-modulus layer disposed along the inside of the tire and a high-modulus layer disposed outside thereof, the high-modulus layer comprises at least one high-modulus ply of cords, and the low-modulus layer comprises at least one low-modulus ply of cords.
Preferably, the cords of each ply are inclined at a bias angle of from 20 to 50 degrees with respect to the tire equator so that the carcass has a bias structure.
The low-modulus layer is composed of two low-modulus plies of low-modulus cords extending between bead portions through a tread portion and sidewall portions and turned up around a bead core disposed in each bead portion.
The high-modulus layer is composed of a single high-modulus ply of high-modulus cords extending between the sidewall portions through the tread portion and terminated at a position radially outward of the bead cores but radially inward of the maximum width position of the carcass.
In this specification, the high-modulus ply or low-modulus ply means that the ply as a complex of the cords and topping rubber has a relatively high or low ply modulus. In practice, however, the ply modulus can be defined as the total of the moduli (initial modulus) of the cords embedded in a unit width (e.g. 5 cm) of the ply as the modulus of rubber is considerably small. Therefore, when the embedded cords are the same modulus, the ply modulus is defined as the product of the modulus of a cord and the cord count per unit width.
It is therefore an object of the present invention to provide a motorcycle tire in which both the rigidity during cornering and the ride comfort during the straight running can be improved.
An embodiment of the present invention will now be described in detail in conjunction with the accompanying drawing.
REFERENCES:
patent: 3980119 (1976-09-01), Nakasaki
patent: 4770222 (1988-09-01), Mezzanotte
Birch & Stewart Kolasch & Birch, LLP
Johnstone Adrienne C.
Sumitomo Rubber Industries Ltd.
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