Tyre Tread Layout Balancing Wet Drainage and Track Grip

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Solution Overview

Problem

High or ultra high performance car tires intended for both road and track usage face conflicting requirements for maintaining high torque transfer, steering precision, and grip on various road conditions, particularly struggling with reduced safety and traction in wet conditions due to the trade-off between groove design for water drainage and tread rigidity.

Innovation Solution

A tire design featuring a tread band with a central region and wide shoulder regions, incorporating transverse grooves and annular portions lacking grooves, which optimizes stiffness distribution for improved handling, traction, and braking performance without compromising water drainage and safety on wet roads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wide and deep grooves are increased in number and size to improve water drainage on wet roads, then draining performance and wet grip are improved, but tread band rigidity is reduced leading to performance decay at high speed on dry grounds and increased noise

Engineering Contradiction:
Improvedraining performance and wet gripVSAvoidtread band rigidity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The tread band is designed with different groove configurations in different regions: the central region has limited grooves to maintain rigidity for high-speed performance, while the shoulder regions have wider and deeper grooves to enhance water drainage. This local differentiation allows each region to optimize for its specific function without compromising overall performance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The tread band is segmented into distinct functional zones (central region and shoulder regions) with different groove patterns. The central region features restricted grooves to preserve structural integrity, while shoulder regions incorporate more extensive grooving for water evacuation, thereby resolving the contradiction between rigidity and drainage through spatial segmentation.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the void-to-rubber ratio is reduced to improve grip and performance on track, then traction and steering precision are improved, but water drainage capability is reduced compromising safety on wet roads

Engineering Contradiction:
Improvetraction and steering precisionVSAvoidwater drainage capability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Different void-to-rubber ratios are applied to different regions of the tread band. The central region maintains a low void-to-rubber ratio to maximize contact patch and grip for high-performance driving, while the shoulder regions have higher void ratios with prominent grooves to ensure effective water drainage, thus resolving the contradiction between grip and drainage through localized property differentiation.

Inventive Principle:
Principle #3Local quality

3Reliability

If transverse grooves are added to improve water evacuation, then draining performance is improved, but tread stiffness is reduced affecting handling and road holding

Engineering Contradiction:
Improvewater evacuationVSAvoidtread stiffness
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

Transverse grooves are selectively positioned in the shoulder regions where they can effectively evacuate water without significantly compromising overall tread stiffness. The central region maintains minimal grooving to preserve the structural rigidity needed for handling and road holding, while shoulder grooves provide targeted water evacuation capability.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4214069B1High performance tyre
Publication Date: 2024.11.13 PIRELLI TYRE SPA
  • EP4214069B1 patent drawingFigure 1
  • EP4214069B1 patent drawingFigure 2
  • EP4214069B1 patent drawingFigure 3

AI summary

A car tyre (1), in particular a high or ultra high performance car tyre also suitable for use on track, is described. The tread band (8) of the tyre has a central region (L1) having a limited extension, separated from two large shoulder regions, respectively an outer shoulder region (L2) and inner shoulder region (L3). At least the outer shoulder region (L2) and the central region (L1) have a set, limited in type, number, size and extension, of transverse grooves. In the tread band (8) there are also annular portions (S1, S2, M) substantially lacking grooves such that the void-to-rubber ratio being zero.