Claims
- 1. A low noise level truck and bus tire including; a carcass composed of at least one ply toroidally extending between a pair of bead cores, and a tread arranged radially outwardly of said carcass and composed on an outer cap rubber layer and an inner base rubber layer, wherein the cap rubber layer is made of a rubber having a dynamic storage modulus (E′c) of not less than 1.0×108 dyn/cm2 and not more than 2.0×108 dyn/cm2 and a loss tangent of not less than 0.15 and not more than 0.35, and the base rubber layer is made of a rubber having a dynamic storage modulus (E′b) of not less than 1.2×108 dyn/cm2 and not more than 2.2×108 dyn/cm2 and a rate of foaming of not less than 5% and not more than 50%, wherein said dynamic storage modulus (E′b) is greater than said dynamic storage modulus (E′c) and the values of dynamic storage modulus and loss tangent are determined by use of a viscoelastic spectrometer operated at an atmospheric temperature of 25° C., a frequency of 52 Hz, an initial strain of 5% and dynamic strain of 1.0%.
- 2. The truck and bus tire according to claim 1, wherein the maximum width of the base rubber layer in its width direction is at least equal to the entire width of the tread of the tire.
- 3. The truck and bus tire according to claim 1, wherein the rate of foaming of the base rubber layer is not less than 10% and not more than 40%.
- 4. The truck and bus tire according to claim 1, wherein a percentage by volume of the base rubber layer to the whole tread is 20% to 70%.
- 5. The truck and bus tire according to claim 4, wherein the percentage by volume of the base rubber layer to the whole tread is 25% to 65%.
- 6. The truck and bus tire according to claim 1, wherein the dynamic storage modulus of the cap rubber layer is not less than 1.05×108 dyn/cm2 but not more than 1.90×108 dyn/cm2.
- 7. The truck and bus tire according to claim 1, wherein the dynamic storage modulus of the base rubber layer is not less than 1.25×108 dyn/cm2 but not more than 2.10×108 dyn/cm2.
- 8. The truck and bus tire according to claim 1, wherein the loss tangent of the cap rubber layer is not less than 0.16 but not more than 0.33.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3-301829 |
Nov 1991 |
JP |
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Parent Case Info
This is a Continuation of application Ser. No. 07/978,413 filed Nov. 18, 1992 now abandoned.
US Referenced Citations (4)
Foreign Referenced Citations (8)
Number |
Date |
Country |
0161793 |
Nov 1985 |
EP |
0301138 |
Feb 1989 |
EP |
0370724 |
May 1990 |
EP |
2150509 |
Jul 1985 |
GB |
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Jun 1985 |
JP |
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Dec 1987 |
JP |
6390402 |
Apr 1988 |
JP |
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Oct 1988 |
JP |
Non-Patent Literature Citations (3)
Entry |
European Search Report dated Feb. 19, 1993. |
Patent Abstracts of Japan, vol. 011, No. 074 (M-568) Mar. 6, 1987 & JP-A-61 229 602 (Ohtsu Tire & Rubber Co., Ltd.) Oct. 13, 1986. |
Patent Abstracts of Japan, vol. 9, No. 132 (M-385)(1855) Jun. 7, 1985 & JP-A-60 015 203 (Bridgestone K.K.) 25. |
Continuations (1)
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Number |
Date |
Country |
Parent |
07/978413 |
Nov 1992 |
US |
Child |
08/320781 |
|
US |