Motorcycle Tire Shoulder Rubber Modulus for Turning Grip
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Solution Overview
Problem
High-performance motorcycle tires face challenges in balancing traction performance with turn performance, leading to early wear, uneven wear, and unsatisfactory grip while turning, despite advancements in spiral belt layers and tread rubber hardness.
Innovation Solution
A pneumatic tire design featuring a narrower spiral belt layer, an inner layer rubber with a lower modulus than the surface layer rubber, extending to the buttress portion, and a specific modulus ratio between the two, to enhance grip and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tread rubber is made to have a high hardness to secure traction performance, then the traction performance is improved, but the grip while turning deteriorates
Solution Approach 1:
The patent applies different rubber hardness properties to different regions of the tread. The shoulder portion uses lower hardness rubber (50-70 Shore A) to improve grip during turning, while the center portion maintains higher hardness rubber (70-90 Shore A) for traction performance. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The tread rubber is segmented into at least two regions: a shoulder portion and a center portion. Each segment is assigned different rubber compound properties (hardness) to achieve both turning grip and traction performance simultaneously, rather than using uniform rubber throughout the tread.
2Ease of operation
If the whole rubber of the shoulder portion is replaced with low hardness rubber to improve grip while turning, then the grip while turning is improved, but early wear and uneven wear are not sufficiently improved
Solution Approach 1:
The patent applies lower hardness rubber specifically to the shoulder portion (50-70 Shore A) to improve turning grip, while the center portion maintains higher hardness (70-90 Shore A) for better wear resistance. This localized application resolves the contradiction by limiting the soft rubber to where it is most beneficial for turning while preserving hard rubber in the high-wear center area.
3Strength
If a spiral belt layer is arranged to increase stiffness in the circumferential direction, then the traction performance is improved, but the grip while turning deteriorates
Solution Approach 1:
The patent combines a spiral belt layer structure (for circumferential stiffness and traction) with localized soft rubber composition in the shoulder portion (for turning grip). The spiral belt provides the necessary structural support for traction while the soft shoulder rubber compensates for reduced turning flexibility, resolving the contradiction between these two performance aspects.
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 achieves improved grip during turns while maintaining wear resistance, with the inner layer rubber's reduced modulus and strategic placement contributing to better warm-up performance and reduced wear.
Implementation Method 1
an inner layer rubber having a smaller modulus at 300% elongation at room temperature than that of a surface layer rubber is arranged; the inner layer rubber extends to a buttress portion
Data Source
AI summary
Provided is a pneumatic tire for a motorcycle which does not produce a failure such as early wear or uneven wear and which has improved grip while turning.The pneumatic tire for a motorcycle is a pneumatic tire for a motorcycle including a ring-shaped tread portion. The tire has, inside in the tire radial direction of the crown portion, at least one spiral belt layer having a width narrower than the width of the tread portion; at the shoulder portion of the tread portion, an inner layer rubber having a smaller modulus at 300% elongation at room temperature than that of a surface layer rubber is arranged; the inner layer rubber extends to a buttress portion; and the range of the ratio of the moduli between the inner layer rubber and the surface layer rubber is from 0.3 to 0.9.