Solid Tyre Wear Indicator Layer Using Color Contrast

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Solution Overview

Problem

Existing solid tyres lack effective means to visually signal the actual end of their service life, leading to premature replacement and underutilization of their potential lifespan.

Innovation Solution

A solid tyre with a layer for indicating excessive wear made from a compound of rubber, silica, plasticising additives, compatibilizing agents, pigments, and protective agents, which is visibly distinct from the tread and resistant to heat, ensuring the tyre's durability and visibility of wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional wear indicators (60J line) are used, then the tyre structure is simple, but the wear indication is inaccurate and does not reflect actual service life

Engineering Contradiction:
Improvewear indication accuracyVSAvoidindicator structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies color change principle by incorporating pigments into different layers of the tyre tread. The indicator layer contains pigments that create a visible color contrast with the tread compound, allowing users to visually detect wear progression. When the tread wears down to the indicator layer, the different color becomes visible, providing accurate wear indication without complex mechanical devices.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent uses composite materials by creating a multi-layered tread structure with different compounds. The indicator layer is formulated as a composite material with distinct physical and visual properties compared to the main tread compound. This layered composite approach enables differentiated wear indication while maintaining the overall structural integrity of the tyre.

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If the tread is made thicker to increase service life, then the tyre durability improves, but the time to detect actual wear endpoint is delayed

Engineering Contradiction:
Improvetyre service lifeVSAvoidtime to detect wear endpoint
Core Design Contradiction:
Duration of action of stationary objectVSLoss of time

Solution Approach 1:

The patent applies segmentation by dividing the tread into multiple functional layers: a main tread layer for durability and an indicator layer for wear detection. This segmented structure allows the tyre to maintain thick tread for extended service life while the embedded indicator layer provides timely visual feedback when wear reaches critical levels, eliminating the time loss associated with undetected wear.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by pre-positioning the wear indicator layer within the tread structure during manufacturing. This allows the indicator to be ready and visible before wear occurs, enabling users to detect the wear endpoint at the precise moment it is reached, rather than discovering it after excessive wear has already compromised safety.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If visual signaling means are added to indicate wear, then wear detection accuracy improves, but the tyre manufacturing complexity increases

Engineering Contradiction:
Improvewear detection accuracyVSAvoidtyre manufacturing ease
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent merges the wear indicator function with the existing tread structure by integrating the indicator layer directly into the tread compound during the vulcanization process. This combining approach incorporates visual signaling capabilities into the standard tyre manufacturing workflow, avoiding separate assembly steps and minimizing increases in manufacturing complexity while achieving accurate wear detection.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4051514B1Solid tyre provided with means for signalling the state of excessive wear
Publication Date: 2025.11.12 YOKOHAMA TWS SPA
  • EP4051514B1 patent drawingFigure 1~2
  • EP4051514B1 patent drawingFigure 3~4

AI summary

A solid tyre (4; 8) is described comprising two or more circular layers overlapped in a radial direction. At least the outermost layer is made of elastic material and consists of an external portion or tread (16). The solid tyre (4; 8) furthermore comprises at least one layer for indicating excessive wear (10), arranged in a predefined position inside the outermost portion or tread (16). The layer for indicating excessive wear (10) is made in a colour different from the one of the external portion or tread (16). The layer for indicating excessive wear (10) is made with a specific compound of materials. This specific compound of materials makes the layer for indicating excessive wear (10) easy to see. This specific compound of materials also makes the solid tyre (4; 8) less hysteretic, and therefore less subject to the development of heat, when compared to similar solid tyres according to the prior art.