Layered Tread Tire Structure for Wet Grip After Wear
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Solution Overview
Problem
Conventional tires experience a deterioration in wet performance as the tread groove volume decreases due to wear, necessitating a solution to maintain effective wet performance even after tread wear progression.
Innovation Solution
A tire design featuring a tread portion with a first cap rubber layer and a second cap rubber layer, where the loss tangent of the second rubber layer is larger, and buttress surfaces with outer lateral grooves that shift axially outward as the tread wears, ensuring the second rubber layer is exposed and maintains wet performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the tread groove volume is decreased due to wear of the tread portion, then the tire structure becomes simpler, but the wet performance deteriorates
Solution Approach 1:
The tread rubber is segmented into multiple layers with different loss tangents. The first cap rubber layer (radially outermost) has a lower loss tangent for initial wet performance, while the second cap rubber layer (radially inner) has a higher loss tangent that becomes exposed during wear to maintain wet performance. This segmentation allows different rubber properties to be utilized at different wear stages.
Solution Approach 2:
The tire is designed with predetermined tread edge shift and outer lateral grooves positioned to be exposed during wear. The buttress surfaces are configured with specific inclinations to ensure that as the tread wears, the tread edges shift axially outward, automatically exposing the second cap rubber layer and the outer lateral grooves to maintain wet performance without requiring active adjustment.
2Reliability
If the tread rubber is worn off, then the second rubber layer is exposed providing higher loss tangent, but the tread groove volume is reduced
Solution Approach 1:
The loss tangent parameter is varied across different rubber layers. The first cap rubber layer has a lower loss tangent (δ1) for initial operation, while the second cap rubber layer has a higher loss tangent (δ2 > δ1) that becomes active during wear. This parameter change allows the tire to maintain optimal wet performance characteristics throughout its service life despite tread groove volume reduction.
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 maintains good wet performance even when the tread is worn, with the second rubber layer providing enhanced friction and drainage capabilities, effectively compensating for the reduced tread groove volume.
Implementation Method 1
a loss tangent δ2 of the second cap rubber compound is larger than a loss tangent δ1 of the first cap rubber compound
Data Source
AI summary
A tire comprises a tread portion having a tread surface and buttress surfaces. The buttress surfaces have inclinations such that the tread edges shift axially outwards as the tread portion is worn off. The tread rubber includes a radially outermost first rubber layer and a radially inner second rubber layer. The loss tangent δ2 of the second rubber layer is larger than the loss tangent δ1 of the first rubber layer. One of or each of the buttress surfaces is provided with an outer lateral groove. The outer lateral groove is located axially outside the tread edge when the tire is new, and when the tread portion is worn off and the tread edge shifts axially outward, the outer lateral groove is at least partially located axially inward of the tread edge.