Pneumatic Tire Tread Layout for Conductivity and Low Rolling Resistance

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Solution Overview

Problem

Existing pneumatic tires face challenges in achieving both enhanced electrical conductivity and wet steering stability while maintaining low rolling resistance, as silica-containing rubber degrades electrostatic charging prevention and the position of electrically conductive portions may not sustain high ground contact pressure throughout the tire's life.

Innovation Solution

A pneumatic tire design with bulging land portions incorporating electrically conductive rubber in specific regions, excluding a 5% width from the bulging apex, ensures consistent exposure and improved conductivity, while using non-conductive rubber for reduced rolling resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If silica content is increased in rubber compounds to reduce rolling resistance, then rolling resistance performance is improved, but electrical conductivity is degraded

Engineering Contradiction:

Improverolling resistanceVSAvoidelectrical conductivity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The tread portion is segmented into multiple rubber compounds with different properties: silica-containing non-conductive rubber in regions requiring low rolling resistance, and electrically conductive rubber without silica in regions requiring electrostatic discharge. This spatial segmentation allows each material to perform its optimal function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different local regions of the tread portion are assigned different material qualities: the first region (including maximum bulging region) uses electrically conductive rubber for electrostatic discharge, while the second region uses silica-containing non-conductive rubber for low rolling resistance. This local differentiation resolves the contradiction by allowing both properties to coexist in different locations.

Inventive Principle:

Principle #3Local quality

2Reliability

If electrically conductive rubber is placed in the maximum bulging region to ensure road contact, then electrical conductivity is improved, but unvulcanized rubber flows into this region during vulcanization, burying the conductive portion

Engineering Contradiction:

Improveelectrical conductivityVSAvoidexposure of conductive portion

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The mold is designed with a protrusion that contacts the tire at the maximum bulging region before and during vulcanization. This preliminary action prevents unvulcanized rubber from flowing into the first region by maintaining physical separation, ensuring the electrically conductive rubber remains exposed after vulcanization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mold protrusion acts as an intermediary element between the electrically conductive rubber and the unvulcanized rubber. It physically separates these two materials during vulcanization, preventing contamination while allowing the conductive rubber to maintain its exposure for electrical contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the electrically conductive portion is inclined toward the first edge to ensure road contact, then electrical conductivity is improved, but the position of highest ground contact pressure shifts over time, reducing sustained conductivity performance

Engineering Contradiction:

Improveelectrical conductivityVSAvoidsustained conductivity performance

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The first region is designed to serve multiple functions: it provides electrical conductivity for electrostatic discharge, maintains road contact through the mold protrusion, and accommodates shifts in ground contact pressure position over time. This multi-functionality ensures sustained conductivity performance throughout the tire's service life.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The design accounts for parameter changes over time, specifically the shift in ground contact pressure position. By designing the first region with sufficient width and positioning it to accommodate these changes, the electrical conductivity function is maintained throughout the tire's life, from new condition to terminal wear stages.

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

The tire achieves enhanced electrical conductivity, maintains wet steering stability, and reduces rolling resistance by ensuring the conductive rubber is exposed and uniformly distributed, preventing non-conductive rubber flow during vulcanization.

Implementation Method 1

an electrically conductive portion made of electrically conductive rubber... connected to a tire internal structure material electrically connected to a rim... on the road contact surface

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12420599B2Pneumatic tire and green tire manufacturing method

Publication Date: 2025.09.23 THE YOKOHAMA RUBBER CO LTD

AI summary

With a pneumatic tire mounted on a regular rim, inflated to a regular internal pressure, and in an unloaded state, in a tire meridian cross-sectional view, electrically conductive rubber is formed in a region corresponding to a bulging land portion except for a region with a width of 5% of a width of the bulging land portion and being centered at a bulging apex position bulging most toward an outer side of the bulging land portion in a tire radial direction.