Multi-stage Tire Tread Design for Wet Performance
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Solution Overview
Problem
Tire manufacturers face the challenge of improving worn tire performance, especially in wet or snow conditions, without increasing new tire performance parameters such as void content and rolling resistance, which often results in reduced tread stiffness and increased wear rates.
Innovation Solution
A multi-stage tire tread design with varying wear layers and features, including outer and inner wear layers, longitudinal grooves with negative draft angles, and undulating sipes, which maintain void content and rigidity across the tire's lifespan, ensuring consistent performance in both new and worn states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tread features are altered or surface void is increased to improve worn wet performance, then worn tire performance is improved, but new tire void content increases beyond desired levels and tread stiffness is reduced
Solution Approach 1:
The tread is divided into multiple wear layers with different void content characteristics. The first wear layer has lower surface void than the second wear layer, allowing the tread to maintain stiffness when new while developing higher void content and flexibility as it wears, thereby improving worn wet performance without sacrificing new tire stiffness
Solution Approach 2:
The tread is designed with predetermined wear layers that will expose different void content characteristics at different stages of wear. The multi-stage wear pattern is built in advance during manufacturing, so that as the tread wears down, it transitions through predetermined stages of void content and stiffness changes that optimize performance at each wear stage
2Reliability
If tread compound is changed to improve worn tire performance, then worn tire performance is improved, but wear rate and rolling resistance increase beyond desired parameters
Solution Approach 1:
Different wear layers are assigned different void content characteristics and potentially different compound formulations optimized for their specific wear stage. The first wear layer uses a compound optimized for new tire durability and low rolling resistance, while the second wear layer exposes a compound formulation optimized for worn tire wet performance, allowing each layer to perform its specific function without compromise
Data Source
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AI summary
Particular embodiments of the present invention include a multi-stage tire tread having two or more wear layers comprising an outer wear layer and one or more inner wear layers arranged within the thickness of the tread below the outer wear layer. One or more outer grooves are arranged within the outer wear layer, while one or more inner grooves arranged within at least one of the one or more inner wear layers. The tread further includes a volumetric void ratio equal to approximately 0.25 to 0.40 in the unworn condition and approximately 0.25 to 0.40 in a worn condition where the outer, ground-engaging side is arranged along one of the inner wear layers in the worn condition, the tread further having a contact surface ratio equal to approximately 0.66 - 0.72 in the unworn condition and approximately 0.56 - 0.66 in the worn condition.