Tyre Tread Pattern with Variable Lateral Rigidity for Winter Adhesion
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Solution Overview
Problem
Winter tires tend to skid sideways on snowy or icy surfaces due to uneven tread band support on bends, leading to loss of lateral adhesion at reduced speeds without adequate warning to the driver, as the total lateral rigidity of the tread band cannot withstand tangential stresses effectively.
Innovation Solution
The tire's tread pattern is configured with shoulder blocks inclined at 70° to 90°, intermediate blocks at 10° to 40°, and central blocks with alternating longitudinal directions, along with transverse notches and sipes, to achieve a progressive decrease in specific lateral rigidity from the axial ends to the equatorial plane, allowing for slight yielding on bends and improved adhesion on snowy and icy surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tread band has high total lateral rigidity to withstand tangential stresses, then road-holding on dry or wet surfaces is maintained, but the tyre cannot provide early warning of adhesion loss on snowy or icy surfaces
Solution Approach 1:
The tread band is designed with non-uniform lateral rigidity distribution: shoulder regions have lower lateral rigidity to allow slight yielding and provide warning, while central regions maintain higher lateral rigidity for stable road-holding on dry or wet surfaces. This local differentiation resolves the contradiction by allowing the tyre to exhibit different mechanical characteristics in different regions.
Solution Approach 2:
The tread band is segmented into shoulder regions and central regions with distinct rigidity characteristics. The shoulder blocks are configured to provide lower lateral rigidity, while central blocks maintain higher rigidity. This segmentation allows the tyre to simultaneously achieve warning capability through shoulder yielding and stable road-holding through central region support.
2Object-generated harmful factors
If the tread band has low total lateral rigidity to allow yielding on bends, then early warning of adhesion loss is provided, but road-holding on dry or wet surfaces deteriorates
Solution Approach 1:
Different regions of the tread band are assigned different rigidity levels: shoulder regions with lower rigidity for warning functionality, and central regions with higher rigidity for maintaining road-holding performance on various surfaces.
Solution Approach 2:
The tread band is divided into functional segments where shoulder blocks provide yielding capability for early warning, while central blocks provide structural support for reliable road-holding on dry or wet surfaces.
3Device complexity
If the tread band has uniform lateral rigidity distribution, then structural simplicity is maintained, but uneven support on bends occurs leading to skidding
Solution Approach 1:
The tread band features non-uniform lateral rigidity distribution with lower rigidity at shoulder regions and higher rigidity at central regions. This gradient distribution optimizes bending behavior by allowing controlled yielding at shoulders while maintaining support in central regions, preventing skidding on bends.
Solution Approach 2:
The tread band design introduces asymmetry in rigidity distribution along the width, with shoulder regions deliberately designed to be more compliant than central regions. This asymmetric rigidity profile improves lateral adhesion by matching the stress distribution pattern during cornering.
Data Source
Figure 1~2
Figure 3~4
AI summary
A method for improving the control of the road-holding of a tyre (1, 100), which includes a tread band (2), on which there is defined a central region (6) which is developed symmetrically about an equatorial plane (M) of the tread band and a pair of shoulder regions (7) which are axially opposite the central region, comprises: - providing respective pluralities of shoulder blocks (11), central blocks (10) and intermediate blocks (12) which are arranged in succession along the circumferential development of the shoulder region and the central region, - configuring the shoulder blocks (11) in order to obtain shoulder regions (7) having values of specific lateral rigidity which decrease with a reduction in the distance from the equatorial plane (M) starting from a maximum value in the region of an axial end (4a, 4b) of the tread band, - configuring the central blocks (10) and the intermediate blocks (12) in order to obtain a central region (6) having values of specific lateral rigidity which increase with an increase in the distance from the equatorial plane starting from a minimum value in the region of the equatorial plane, and less than the values of specific lateral rigidity of the shoulder regions, so as to determine a progressive trend of the values of specific lateral rigidity between the axial end and the equatorial plane, wherein the minimum value of specific lateral rigidity is between 65% and 85% of the maximum value of specific lateral rigidity.