Tire Tread Stiffness Control via Carcass Turn-Up and Band Alignment
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Solution Overview
Problem
Tires for two-wheeled automotive vehicles experience a significant difference in tread stiffness between straight running and cornering, leading to deterioration in ground contact feeling and transient characteristics during full-bank cornering.
Innovation Solution
A tire design featuring a carcass ply with turn-up portions, a belt with layered layers, and a band positioned between the belt and tread, where the outer ends of the layers and turn-up portions are closely aligned to minimize stiffness differences, with specific dimensions and layer ratios to enhance cornering stability and transient characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the belt and band are layered over the carcass to increase tread stiffness for high cornering power, then cornering stability is improved, but the difference in tread stiffness between straight running and cornering regions increases, deteriorating transient characteristics when shifting to full-bank cornering
Solution Approach 1:
The carcass ply is designed with different configurations in different regions: the main portion has cords extending in the circumferential direction to provide overall structural support, while the turn-up portions have cords extending in the radial direction to specifically address the stiffness characteristics at the tread ends during cornering. This local differentiation allows the tire to maintain high cornering stability while reducing the stiffness difference between regions, improving transient characteristics when transitioning to full-bank cornering.
2Force
If the stiffness of the tread is increased in the shoulder region including the tread end, then cornering power is improved, but the ground contact feeling for the rider deteriorates during full-bank cornering
Solution Approach 1:
The turn-up portions of the carcass ply are specifically designed with cords extending in the radial direction to provide localized stiffness enhancement at the tread ends during cornering, while the main portion maintains circumferential cord orientation for overall support. This localized approach improves cornering power without excessively stiffening the entire tread, preserving ground contact feeling during full-bank cornering.
Solution Approach 2:
The tire employs a composite structure combining the carcass ply with circumferential cords and turn-up portions with radial cords, creating a multi-directional reinforcement system. This composite cord arrangement allows the tire to exhibit different stiffness characteristics in different directions and regions, achieving high cornering power while maintaining acceptable ground contact feeling during extreme cornering maneuvers.
Data Source
AI summary
In a tire 2 for a two-wheeled automotive vehicle, a carcass ply 24 is extended on and between one bead 8 and the other bead 8 along inner sides of a tread 4 and sidewalls 6, and includes a main portion 24a and turn-up portions 24b, which are formed by the carcass ply 24 being turned up around the beads 8 from an inner side toward an outer side in an axial direction. An outer end Pp of each turn-up portion 24b is positioned outward of a tread end Pe in a radial direction. A band 14 is positioned between a belt 12 and the tread 4, such that the band 14 covers the belt 12. An outer end P1 of an inner layer 28 layered over a carcass 10 and the outer end Pp of the turn-up portion 24b are positioned facing each other.