Motorcycle Tire Groove Pattern and Rubber Modulus for Wet Grip
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Solution Overview
Problem
Motorcycle tires face a challenge in maintaining rigidity during turning on wet surfaces, which compromises steering stability and grip performance, as existing techniques that enhance grip by reducing shoulder rigidity also affect straight-line travel rigidity.
Innovation Solution
A motorcycle tire design featuring a central rubber with higher modulus and shoulder rubber with lower modulus, combined with specific groove patterns that include inclined first, second, and third grooves, arranged to maintain rigidity and improve wet grip performance during turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-hardness rubber compound is arranged on the shoulder portion to improve wet grip performance during turning, then grip performance is improved, but the rigidity of the shoulder portion is reduced and steering stability is deteriorated
Solution Approach 1:
The patent applies local quality by using a low-hardness rubber compound specifically in the shoulder portion (both-side rubber) while maintaining higher hardness in the central portion (central rubber). This localized differentiation allows the shoulder to provide enhanced wet grip performance during turning without compromising the overall structural rigidity needed for steering stability, as the central portion maintains its stiffness.
2Object-generated harmful factors
If lateral grooves are provided across the entire tread grounding portion to improve drainage, then drainage performance is improved, but the rigidity of the tread is reduced
Solution Approach 1:
The patent segments the drainage function by providing lateral grooves only in specific regions (shoulder portions) rather than across the entire tread grounding portion. The grooves are positioned to extend from the tread end toward the center but terminate before reaching the central high-rigidity area, thus improving drainage performance while preserving the overall tread rigidity needed for stable straight-line travel.
3Strength
If the boundary between central rubber and both-side rubber is positioned closer to the tire equator to maintain straight-line rigidity, then straight-line travel rigidity is improved, but the shoulder portion grip performance during turning is reduced
Solution Approach 1:
The patent applies partial action by providing lateral grooves that extend partially into the central rubber region but terminate before reaching the tire equator. This partial penetration allows sufficient water drainage from the shoulder area while maintaining the central rubber's rigidity for straight-line travel. The groove positioning is optimized to achieve the minimum necessary drainage function without excessive intrusion into the high-rigidity central zone.
Data Source
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AI summary
Provided is a motorcycle tire with improved wet grip performance while ensuring the rigidity during turning. Provided is a motorcycle tire in which: a tread portion is composed of a central rubber (11C) and a both-side rubber (11S) having a lower modulus than the central rubber; the boundary is from the tire equator to from 1/2 to 3/4 of the half width of the peripheral length; a tire grounding portion includes a first groove, a second groove, and a third groove; a bent portion of the first groove and a bent portion of the second groove, an inner side end and an outer side end in the width direction of the second groove, an inner side end in the width direction of the third groove are located at positions from 1/8 to 3/8, from 1/4 to 1/2, from 1/16 to 3/16, from 5/8 to 7/8, and from 1/2 to 5/8 of the half width of the peripheral length from the tire equator; the angles θ1, θ2, θ3, θ4, and θ5 formed by a long groove portion and a short groove portion of the first groove, an outer side groove portion and an inner side groove portion of the second groove, and the third groove with respect to the circumferential direction satisfy θ1 ≈ θ2 ≈ θ3 ≈ θ5, and θ1 > θ4; and a distance a between the first groove and the second groove, a distance b between the second groove and the third groove, and a distance c between the third groove and the first groove satisfy a ≈ b ≈ c.