Tire Bead Bottom Structure for Slippage and Toe Chipping
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Solution Overview
Problem
Pneumatic tires experience bead toe chipping and reduced air sealing when mounted on wheel rims due to strong contact and high torque during severe running conditions, particularly in car racing, leading to tire/rim slippage and potential damage.
Innovation Solution
The tire design incorporates a bead bottom surface with an axially inner region of canvas chafer for injury resistance and an axially outer region of soft sidewall rubber for increased friction, preventing bead toe damage and slippage without additional components, using a toroidal carcass and reinforcing belts for structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bottom surfaces of the bead portions are formed from hard rubber (chafer or clinch rubber) to suppress tire/rim slippage, then the resistance to slippage under severe running conditions is improved, but the bead toe is liable to be chipped off when the tire is mounted on a wheel rim
Solution Approach 1:
The bead bottom surface is divided into two regions with different material properties: the axially inner region (including bead toe) is formed by canvas chafer for damage resistance, while the axially outer region (including bead heel) is formed by hard rubber for slippage resistance. This local differentiation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The bead bottom surface employs a composite structure combining canvas chafer and hard rubber materials. The canvas chafer provides toughness and resistance to chipping at the bead toe, while the hard rubber provides high friction and resistance to tire/rim slippage at the bead heel, creating a composite solution that leverages the strengths of both materials.
2Strength
If the lateral stiffness is increased in a pneumatic tire for car racing, then the steering performance is improved, but the bead toe is more liable to be chipped off due to strong contact with the rim flange
Solution Approach 1:
The invention applies local quality differentiation at the bead bottom surface, where the canvas chafer is specifically positioned at the axially inner region including the bead toe to provide localized protection against chipping damage, while allowing the rest of the tire structure to maintain high lateral stiffness for racing performance.
Solution Approach 2:
The canvas chafer is pre-installed at the bead toe region before the tire is mounted on the wheel rim, providing beforehand protection against the strong contact forces and potential chipping damage that will occur during mounting and subsequent use under severe racing conditions.
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
This design effectively suppresses tire/rim slippage and bead toe damage while maintaining air sealing, enhancing steering stability and durability without increasing manufacturing complexity.
Implementation Method 1
the axially outer region is formed by the sidewall rubber extended radially inwardly from the sidewall portion
Data Source
AI summary
A pneumatic tire comprises: a tread portion; a pair of sidewall portions; a pair of bead portions each with a bead core embedded therein; a toroidal carcass extending between the bead portions; and a sidewall rubber disposed axially outside the carcass in each of the sidewall portions. The bead portion has a bead bottom surface which contacts with a bead seat of a wheel rim when the tire is mounted thereon. The bead bottom surface comprises an axially inner region including a bead toe and an axially outer region including a bead heel. The axially inner region is formed by a canvas chafer. The axially outer region is formed by the sidewall rubber extended radially inwardly from the sidewall portion.