Tread Groove and Rubber Hardness for Worn Tire Wet Grip
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Solution Overview
Problem
Conventional tires lack stability on wet and icy roads when worn, due to reduced grooves and increased rigidity, which affects handling performance.
Innovation Solution
A tire design with a tread portion featuring a main groove extending circumferentially, using rubber with specific hardness parameters and a S50/S0 ratio greater than 1, ensuring improved water drainage and road contact on worn tires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tire uses conventional rubber composition and groove design, then the tire provides adequate initial traction, but the handling stability deteriorates when the tire is worn
Solution Approach 1:
The patent applies parameter changes by specifying precise rubber hardness values at different temperatures (58-75 at 60°C, 70-85 at 0°C) and defining the S50/S0 ratio greater than 1. These parameter specifications ensure that the rubber maintains optimal physical properties throughout the tire's service life, preventing performance deterioration when worn
Solution Approach 2:
The patent implements preliminary action by designing the groove configuration and rubber composition in advance to maintain the S50/S0 ratio greater than 1 throughout the tire's life. This preliminary design ensures that even when the tire is worn, the groove aperture remains sufficient for water drainage and the rubber retains appropriate hardness for traction, thereby maintaining handling stability throughout the service period
2Reliability
If the tire groove depth is increased to improve water drainage, then wet road performance improves, but the tire weight and rolling resistance increase
Solution Approach 1:
The patent applies parameter changes by optimizing the groove dimensions and rubber hardness to achieve effective water drainage without excessive groove depth. The specific hardness parameters (58-75 at 60°C) allow the rubber to maintain flexibility and drainage capability with moderate groove configurations, reducing unnecessary weight
Solution Approach 2:
The patent uses composite materials by formulating a specific rubber composition that combines multiple rubber components and additives to achieve the desired hardness range and wear characteristics. This composite rubber formulation provides both the necessary drainage performance and weight efficiency, eliminating the need for overly deep grooves
Data Source
AI summary
A tire including a tread portion, the tread portion having at least one main groove continuously extending in the tire circumferential direction, the tread portion including a rubber having a hardness at 60° C. of 58 or higher and a hardness at 0° C. of not more than 115% of the hardness at 60° C., the tread portion having a S50/S0 ratio of more than 1, wherein S0 denotes the sea proportion (%) in the tread ground contact surface of the new tire, and S50 denotes the sea proportion (%) when the tread portion is worn until the depth of the main groove reaches 50% of that of the new tire.