Motorcycle Tire Tread Modulus Zoning for Cornering Grip
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Solution Overview
Problem
Existing tires for two-wheeled vehicles face challenges in achieving a high balance between dry and wet gripping performance during high-speed cornering without compromising cornering stability, and conventional methods to enhance gripping performance often deteriorate handleability or result in unsatisfactory activation performance.
Innovation Solution
A tire design with a divided tread portion into five sections, utilizing specific storage modulus, loss tangent, and peak temperature parameters for center, traction, and edge rubbers, along with a composition including styrene-butadiene rubber, butadiene rubber, silica, carbon black, and controlled resin and oil content, enhances gripping performance without impairing cornering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of filler in the tread portion is increased to improve gripping performance during high-speed cornering, then gripping performance is improved, but handleability during tire production deteriorates
Solution Approach 1:
The tread portion is divided into three regions (center, shoulder, and intermediate portions) with different filler contents. The center portion has higher filler content (80-120 parts per 100 parts rubber) for straight-line stability, while the shoulder and intermediate portions have lower filler content (60-100 parts per 100 parts rubber) to maintain flexibility and handleability during production, thus resolving the contradiction between gripping performance and manufacturing ease.
Solution Approach 2:
The tread rubber is segmented into multiple portions with different compositions. By dividing the tread into functionally distinct regions (center, shoulder, intermediate) with optimized filler contents for each, the patent achieves overall gripping performance while maintaining production handleability in the less critical regions.
2Reliability
If a resin is included in the tread portion to improve gripping performance, then gripping performance is improved, but the peak temperature of the loss tangent increases resulting in unsatisfactory activation performance
Solution Approach 1:
The patent applies different resin contents to different tread regions. The center portion has lower resin content (5-30 parts per 100 parts rubber) to maintain lower peak temperature and better activation performance, while the shoulder and intermediate portions can have higher resin content (10-50 parts per 100 parts rubber) to enhance gripping performance without adversely affecting the overall activation characteristics.
3Reliability
If the tread portion is designed for high gripping performance during cornering, then gripping performance is improved, but cornering stability may be impaired
Solution Approach 1:
The patent optimizes the storage modulus E' differently for different tread regions at 60°C. The center portion has E' of 4-8 MPa for straight-line stability, the shoulder portion has E' of 3-6 MPa for cornering grip, and the intermediate portion has E' of 3.5-7 MPa. This regional differentiation allows the tire to achieve both cornering stability and high gripping performance during cornering maneuvers.
Data Source
Figure 1~2
AI summary
An object of the present disclosure is to provide a tire for two-wheeled vehicles having excellent gripping performance without impairing cornering stability. In order to solve the above problem, the present disclosure provides a tire for two-wheeled vehicles including a pair of bead portions and a pair of sidewall portions, and a tread portion continuous with both of the sidewall portions. The tread portion is divided into five sections on a tread portion surface in a tire width direction, the five sections including a center portion including a tire equatorial plane, a pair of edge portions each including a tread edge, and a pair of traction portions each disposed between the center portion and the edge portion. The storage modulus E' at 60°C of a center rubber constituting the center portion, a traction rubber constituting the traction portion, and an edge rubber constituting the edge portion satisfies the following formulae (1) and (2): E' of the center rubber > E' of the edge rubber > E' of the traction rubber ... (1), and E' of the edge rubber > an average value of E' of the center rubber and E' of the traction rubber ... (2).