Motorcycle Tire Tread with Intermediate Modulus Zones
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Solution Overview
Problem
Motorcycle tires face challenges in balancing grip force and handling stability during cornering and straight running, with existing designs experiencing unstable behavior during transitions due to rapid changes in contact regions.
Innovation Solution
A tire design featuring a center region with high modulus crosslinked rubber for straight running stability, shoulder regions with low modulus for cornering grip, and middle regions with moduli intermediate between the two, minimizing rapid characteristic changes during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft tread is employed to obtain high coefficient of friction, then gripping property in cornering is improved, but handling stability in straight running deteriorates
Solution Approach 1:
The tread is divided into three regions with different rubber compositions and hardness: the center region uses harder rubber for stability during straight running, while the shoulder regions use softer rubber for enhanced grip during cornering. This local differentiation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The tread is segmented into distinct zones (center region, shoulder regions, and intermediate regions) with progressively varying rubber compositions. This segmentation creates a gradient structure that facilitates smooth transition between different riding modes while maintaining both stability and grip characteristics.
2Ease of operation
If the tread has a small radius of curvature to facilitate cornering, then cornering performance is improved, but stability during transition between straight running and cornering deteriorates
Solution Approach 1:
The rubber composition parameters are systematically varied across the tread width, creating a gradient in hardness and modulus. The intermediate regions contain rubber compositions with properties between the center and shoulder regions, which smooths out the characteristic changes during transition and reduces unstable behavior.
3Speed
If the contact portion moves rapidly between center region and shoulder region during transition, then response to steering input is improved, but motorcycle behavior stability deteriorates
Solution Approach 1:
The intermediate regions act as transitional zones with rubber compositions that serve as intermediaries between the hard center region and soft shoulder regions. These intermediate zones buffer the rapid changes in characteristics during transition, preventing abrupt shifts in motorcycle behavior while still allowing responsive steering input.
Data Source
AI summary
A tire (2) for a motorcycle includes a tread (4). The tread (4) has a center region (18), a pair of shoulder regions (20) and a pair of middle regions (22). In straight running, the center region (18) mainly comes in contact with a road surface. In cornering, the shoulder region (20) mainly comes in contact with a road surface. A modulus (Mm) of a rubber composition in the middle regions (22) is lower than a modulus (Mc) in the center region (18) and is higher than a modulus (Ms) in the shoulder regions (20). A ratio ((Mc−Mm)/(Mm−Ms)) is equal to or higher than 1/3 and is equal to or lower than 3/1. A ratio (Wm/W) is equal to or higher than 0.3 and is equal to or lower than 0.8. A ratio (Wc/W) is equal to or higher than 0.1 and is equal to or lower than 0.4. A ratio (Ws/W) is equal to or higher than 0.1 and is equal to or lower than 0.4.