Run-flat tire with tread reinforcing layer

• US 6,142,204 A
• Filed: 10/20/1998
• Issued: 11/07/2000
• Est. Priority Date: 10/20/1997
• Status: Expired due to Term

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Omoteda, Masanori, Tagashira, Kenji, Yoshioka, Tetsuhiko
• Primary Examiner(s): Johnstone, Adrienne C.
• Application Number:
  US09/175,579
• Time in Patent Office: 749 Days
• Field of Search: 152/517, 152/549, 152/532, 152/533, 152/554, 152/516, 152/537, 152/564
• US Class Current: 152/517
• CPC Class Codes: B60C 13/00 Tyre sidewalls; Protecting, decorating, marking, or the like, thereof B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01
• CPC Class Codes: B60C 15/0045 with ply turn-up up to the belt edges, i.e. folded around the bead core and extending to the belt edges
• CPC Class Codes: B60C 17/0009 comprising sidewall rubber inserts, e.g. crescent shaped inserts
• CPC Class Codes: B60C 2009/1871 with flat cushions or shear layers between belt layers
• CPC Class Codes: B60C 2009/1878 with flat cushions or shear layers between the carcass and the belt
• CPC Class Codes: B60C 2017/0081 comprising special reinforcing means in the crown area
• CPC Class Codes: B60C 9/14 built-up with sheets, webs, or films of homogeneous material, e.g. synthetics, sheet metal, rubber
• CPC Class Codes: B60C 9/18 Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
• CPC Class Codes: Y10T 152/10783 Reinforcing plies made up from wound narrow ribbons
• CPC Class Codes: Y10T 152/1081 Breaker or belt characterized by the chemical composition or physical properties of elastomer or the like

Abstract

A run-flat tire comprises a tread portion, a pair of bead portions, a pair of sidewall portions, a carcass comprising at least one carcass ply extending between the bead portions, a belt disposed radially outside the carcass in the tread portion, and a tread reinforcing layer disposed between carcass plies or alternatively between the carcass and belt, the tread reinforcing layer made of a high elastic modulus rubber compound having a complex elastic modulus E* of from 10 to 30 MPa, a thickness t of from 0.8 to 2.5 mm, and an axial width WA of 0.7 to 1.0 times the tread width TW of the tire.

Claims

1. A run-flat tire comprising:

a tread portion;

a pair of bead portions;

a pair of sidewall portions;

a carcass comprising at least one carcass ply extending between the bead portions to form a carcass main portion;

a belt disposed radially outside the carcass in the tread portion;

a tread reinforcing layer disposed between carcass plies or alternatively between the carcass and belt; and

the tread reinforcing layer being made of a high elastic modulus rubber compound having a complex elastic modulus E* measured at a temperature of 70°

C., a frequency of 10 Hz, and a dynamic distortion of 2% of from 10 to 30 MPa, a thickness t of from 0.8 to 2.5 mm, and an axial width WA of 0.7 to 1.0 times the tread width TW of the tire.

2. The run-flat tire according to claim 1, wherein the sidewall portions are each provided with a sidewall reinforcing layer made of a rubber compound adjoining a carcass main portion and comprising a tapered radially outer part and a tapered radially inner part.

3. The run-flat tire according to claim 2, wherein

said sidewall reinforcing layer has a radially outer end spaced apart from the axially outer ends of the tread reinforcing layer.

4. The run-flat tire according to claim 1, further comprising:

said carcass comprises two carcass plies each extending between the bead portions and turned up around a bead core in each of the bead portions from the axially inside to outside of the tire so that each of the two carcass plies comprises a pair of turnup portions and a main portion therebetween;

said tread reinforcing layer is disposed between said two carcass plies;

the turnup portions of at least one of said carcass plies extend from the bead portions to the tread portion so that the edges thereof are secured under the belt;

said sidewall portions are each provided with a sidewall reinforcing layer disposed between one of said turnup portions extending to the tread portion and the axially inwardly adjacent carcass ply main portion;

said sidewall reinforcing layer is made of a hard rubber compound having a JIS-A hardness of from 60 to 80 degrees; and

said sidewall reinforcing layer tapers radially inwardly and outwardly and the maximum thickness thereof is in the range of from 3 to 5 mm.

5. The run-flat tire according to claim 4, further comprising:

on the axially inside of the carcass there is provided only a thin inner liner for air sealing; and

said sidewall portions are provided between the main portions of said two carcass plies with no rubber layer other than topping rubber for the carcass plies.