Pneumatic Tire Tread Arc Design for Wear and Stability
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Solution Overview
Problem
Conventional pneumatic tires face challenges in achieving balanced wear resistance, braking performance, and rollover resistance, particularly when adjusting the crown shape to maintain rollover resistance and reduce cornering force, which can lead to increased contact pressure and reduced braking performance.
Innovation Solution
A pneumatic tire design featuring a tread surface formed of multiple arcs with specific curvature radii and dimensions, including a center arc, shoulder-side arc, and shoulder arc, optimized by formulas F1 to F5, to enhance ground contact area, contact pressure uniformity, and cornering force management under varying loads, along with the use of a compound with a 300% tensile modulus of 5 MPa to 10 MPa for the cap tread and a base rubber layer with JIS A hardness of 48 to 60, and bead fillers with appropriate stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the crown shape is adjusted to reduce maximum cornering force and maintain rollover resistance, then rollover resistance is improved, but contact pressure at shoulder portions increases excessively causing wear
Solution Approach 1:
The tread surface is designed with different curvature radii in different regions: a larger curvature radius in the center portion and a smaller curvature radius in the shoulder portions. This local differentiation allows the center to maintain larger contact area for stability while shoulders have optimized contact pressure distribution to prevent wear, resolving the contradiction between rollover resistance and shoulder wear resistance.
2Stability of the object's composition
If ground contact areas around shoulders are reduced to adjust crown shape, then rollover resistance is maintained, but braking performance deteriorates due to reduced ground contact area
Solution Approach 1:
The patent applies different curvature characteristics to different tread regions: the shoulder portions have smaller curvature radii that optimize contact pressure for rollover resistance, while the center portion maintains larger curvature radius for adequate ground contact area, ensuring both rollover resistance and braking performance are achieved simultaneously.
3Object-affected harmful factors
If the tread is formed with a crown shape to reduce biased wear, then wear uniformity is improved, but handling stability and cornering force are compromised
Solution Approach 1:
The tread surface employs a multi-arc crown shape with varying curvature radii across different regions. The center portion has larger curvature radius to maintain handling stability and cornering force, while shoulder portions have smaller curvature radii to achieve uniform wear distribution, thus resolving the contradiction between wear uniformity and handling stability.
Data Source
AI summary
A tread surface includes a center arc, a shoulder-side arc, and a shoulder arc, and is formed such that a value given by F1=L1/(TDW×0.5) falls in the range of 0.64≦F1≦0.7, a value given by F2=TR1/OD falls in the range of 1.2≦F2≦2.0, a value given by F3=TR2/TR1 falls in the range of 0.1≦F3≦0.2, and a value given by F4=(β×TDW)/(100×SW) falls in the range of 0.35≦F4≦0.48, where L1 is outline range being a width from an equatorial plane to an edge of the center arc, TDW is extended tread width, TR1 is curvature radius of the center arc, TR2 is curvature radius of the shoulder-side arc, OD is tire outside diameter, SW is total width, and β is aspect ratio.