Off-Road Tire Crown Block Structure for Grip and Durability
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Solution Overview
Problem
Tires designed for off-road use face challenges in maintaining durability while achieving high grip performance on rocky and snowy/muddy surfaces, as existing designs often compromise between traction and longevity.
Innovation Solution
The tire features a tread portion with shoulder main grooves, crown blocks having a chamfered portion and step-shaped portions, which enhance grip on rocky surfaces and durability by preventing local chipping and increasing bending rigidity, and improve traction on snowy/muddy surfaces through the shearing action of the step-shaped portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crown block is designed with simple shape for durability, then the block strength is improved, but the grip performance on rocky and snowy/muddy surfaces deteriorates
Solution Approach 1:
The crown block is segmented into multiple functional regions: a ground contacting surface for grip, a chamfered portion for durability, and a main body portion with step-shaped portions for structural integrity. This segmentation allows each region to optimize its specific function while working together as a unified block structure.
Solution Approach 2:
Different regions of the crown block are given different geometric properties tailored to their specific functions. The ground contacting surface has specific roughness for grip, the chamfered portion has angled surfaces for chip prevention, and the main body has step-shaped portions for rigidity. This local differentiation resolves the contradiction between overall strength and localized grip performance.
2Reliability
If the crown block is designed with complex shape for grip performance, then the grip on rocky and snowy/muddy surfaces is improved, but the durability of the block deteriorates
Solution Approach 1:
The chamfered portion is designed in advance to prevent local chipping before it can occur during operation. By providing this protective geometric feature proactively, the block maintains its structural integrity and durability while still achieving the necessary grip performance through the ground contacting surface.
Solution Approach 2:
The step-shaped portions are pre-configured in the main body to provide necessary bending rigidity before the tire encounters demanding terrain. This preliminary structural preparation ensures the block can withstand stresses without deforming excessively, maintaining both grip performance and durability.
3Strength
If the chamfered portion is made large to prevent chipping, then the durability is improved, but the ground contact area is reduced
Solution Approach 1:
The chamfered portion is designed with moderate dimensions that provide sufficient protection against chipping without excessively reducing the ground contact area. The step-shaped portions in the main body compensate for any potential strength loss, allowing the chamfered portion to be optimized for chip prevention while maintaining adequate contact area through the combined structure.
Data Source
AI summary
A tire includes a tread portion. The tread portion includes a pair of shoulder main grooves and a plurality of crown blocks. Each of the crown blocks includes a ground contacting surface, a chamfered portion arranged so as to surround the entire circumference of the ground contacting surface, and a main body portion arranged inside the chamfered portion in a tire radial direction. The main body portion is provided with at least one step-shaped portion that is bent stepwise in a transverse cross section orthogonal to the ground contacting surface.