Run-Flat Tire Sidewall Structure for Durability and Ride Comfort
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Solution Overview
Problem
Run flat tires with side-reinforcing rubber experience a decrease in ride comfort due to an increase in vertical spring coefficient, compromising durability and comfort.
Innovation Solution
A run flat tire design with a low elastic modulus portion in the sidewall, located between 50% and 80% of the tire cross-sectional height from the bead baseline, and a specific thickness ratio, combined with a carcass structure to reduce bending rigidity and maintain load support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If side-reinforcing rubber with high elastic modulus is used to ensure run flat durability, then run flat durability is improved, but ride comfort deteriorates due to increased vertical spring coefficient
Solution Approach 1:
The side-reinforcing rubber is designed with non-uniform thickness: a thicker first region (50-70% of cross-sectional height) provides enhanced run flat durability where load support is critical, while a thinner second region (70-100% of cross-sectional height) reduces the vertical spring coefficient to improve ride comfort. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The invention changes the thickness parameter of the side-reinforcing rubber along the radial direction, creating a gradient structure where thickness varies from 5mm to 10mm. This parameter variation allows the tire to maintain high durability in the load-bearing region while reducing stiffness in the upper region, thereby improving ride comfort without sacrificing run flat capability.
2Strength
If side-reinforcing rubber is added to provide load support during run flat driving, then run flat capability is improved, but vertical spring coefficient increases causing deterioration in ride comfort
Solution Approach 1:
The side-reinforcing rubber concentrates its thickness in the first region (50-70% of cross-sectional height) where load support is most needed during run flat driving, while maintaining thinner dimensions in the second region. This local quality differentiation provides strong load support capability where required while minimizing the increase in vertical spring coefficient, thus resolving the contradiction between strength and ride comfort.
3Ease of operation
If the tire maximum width position is located closer to the bead baseline to improve ride comfort, then ride comfort is improved, but run flat durability decreases
Solution Approach 1:
The invention positions the tire maximum width in the first region (50-70% of cross-sectional height) where the side-reinforcing rubber provides enhanced thickness and strength. This local reinforcement ensures that even with the maximum width position optimized for ride comfort, the run flat durability is maintained through the concentrated thickness in the critical load-bearing region.
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 design enhances run flat durability while reducing the deterioration in ride comfort and maintaining fuel efficiency.
Implementation Method 1
a part of the side-reinforcing rubber is a low elastic portion with a lower elastic modulus than other portion
Data Source
AI summary
The tire maximum width in the reference condition is the center value or more and the upper limit or less of the tire maximum width specified in the standard, and the tire maximum width position in the reference condition is located at the position, with a distance of more than 50% of the tire cross-sectional height, outward in the tire radial direction from the bead baseline.