Self-Supporting Tyre With Asymmetric Inserts for Lower Rolling Resistance

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Solution Overview

Problem

Existing self-supporting tyres compromise rolling resistance and comfort due to the use of rigid sidewall reinforcing inserts, particularly on the most stressed side, which are necessary for adequate support during deflation.

Innovation Solution

The tyre design incorporates a sidewall reinforcing insert with a lower modulus on the more stressed side and a specific underliner, using an elastomeric compound with a shear modulus of less than 1.25 MPa, combined with reduced reinforcing filler content and white fillers, to improve comfort and reduce rolling resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rigid sidewall reinforcing inserts are used on the most stressed side, then self-supporting capability is improved, but rolling resistance and comfort deteriorate

Engineering Contradiction:
Improveself-supporting capabilityVSAvoidrolling resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies different elastomeric compounds with different shear modulus values to different sidewall regions. Specifically, the first sidewall reinforcing insert uses a compound with G' ≥ 1.25 MPa for adequate support, while the second sidewall reinforcing insert uses a compound with G' < 1.25 MPa to reduce rolling resistance and improve comfort in less critical areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs asymmetrical sidewall reinforcing inserts with different material properties on opposite sides of the tyre. This asymmetrical design allows optimization of each side's characteristics - one side prioritizes support capability while the other prioritizes energy efficiency and comfort, resolving the contradiction between these opposing requirements.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If rigid sidewall reinforcing inserts are used, then self-supporting capability is improved, but comfort deteriorates

Engineering Contradiction:
Improveself-supporting capabilityVSAvoidcomfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies different elastomeric compounds with different shear modulus values to different sidewall regions. Specifically, the first sidewall reinforcing insert uses a compound with G' ≥ 1.25 MPa for adequate support, while the second sidewall reinforcing insert uses a compound with G' < 1.25 MPa to reduce rolling resistance and improve comfort in less critical areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent employs asymmetrical sidewall reinforcing inserts with different material properties on opposite sides of the tyre. This asymmetrical design allows optimization of each side's characteristics - one side prioritizes support capability while the other prioritizes energy efficiency and comfort, resolving the contradiction between these opposing requirements.

Inventive Principle:
Principle #4Asymmetry

3Reliability

If high reinforcing filler content is used, then self-supporting capability is improved, but rolling resistance increases

Engineering Contradiction:
Improveself-supporting capabilityVSAvoidrolling resistance
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies different elastomeric compounds with different shear modulus values to different sidewall regions. Specifically, the first sidewall reinforcing insert uses a compound with G' ≥ 1.25 MPa for adequate support, while the second sidewall reinforcing insert uses a compound with G' < 1.25 MPa to reduce rolling resistance and improve comfort in less critical areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the shear modulus parameter of the elastomeric compound used in the sidewall reinforcing inserts. By using compounds with different G' values (≥ 1.25 MPa and < 1.25 MPa) in different locations, the patent optimizes the balance between self-supporting capability and rolling resistance without relying solely on increasing reinforcing filler content throughout.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances rolling resistance, fuel efficiency, and comfort while maintaining the required self-supporting capabilities, surpassing the performance of conventional asymmetrical inserts by ensuring improved travel distance and reduced stress on the tyre.

Implementation Method 1

a first sidewall reinforcing insert, said first insert being incorporated into the respective first sidewall structure of the tyre, at a position axially internal to the respective first sidewall, and a second sidewall reinforcing insert, said second insert being incorporated into the respective second sidewall structure

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4267407B1A self-supporting tyre for automotive wheels
Publication Date: 2025.08.13 PIRELLI TYRE SPA
  • EP4267407B1 patent drawingFigure 1

AI summary

The present invention relates to a self-supporting tyre (100) for motor vehicles which comprises sidewall reinforcing inserts (113A, 113B) with different stiffness. In particular, the sidewall reinforcing insert on the side of the tyre most stressed during driving is less rigid than the sidewall reinforcing insert on the less stressed side. The tyre of the invention exhibits a reduced rolling resistance and better comfort in normal driving and an unexpected increase in mileage in run-flat driving.