Pneumatic Tire Shoulder Grooves and Rubber Composition
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Solution Overview
Problem
Pneumatic tires face challenges in achieving balanced steering stability and braking performance on both dry and wet road surfaces, with existing technologies not adequately addressing these requirements.
Innovation Solution
A pneumatic tire design featuring at least three circumferential main grooves, shoulder land portions with shoulder lateral grooves and axial sipes, and a specific rubber composition of not less than 10 parts by mass of carbon black and 90 parts by mass of silica per 100 parts of rubber, optimizing the length and distribution of these features to enhance contact area and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of lateral grooves and longitudinal grooves is increased to improve braking performance on wet road surfaces, then steering stability on dry road surfaces deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the groove configurations in different tread regions. The shoulder land portions have lateral grooves extending in the tire axial direction to improve wet braking, while the center land portion has a different groove pattern optimized for dry steering stability. This localized differentiation allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The tread pattern is segmented into distinct functional zones: shoulder land portions with lateral grooves for wet braking performance, center land portion with different groove configuration for dry steering stability, and transition regions. This segmentation allows independent optimization of each zone's characteristics to resolve the contradiction between wet braking and dry steering performance.
2Reliability
If groove volumes are increased to enhance braking performance, then steering stability deteriorates
Solution Approach 1:
The patent implements local quality by restricting large groove volumes to specific regions (shoulder land portions) where they are needed for braking performance, while maintaining smaller groove volumes in the center land portion to preserve steering stability. The lateral grooves in shoulder portions have controlled lengths (10-30% of tread width) to provide adequate water evacuation without excessive volume that would compromise structural integrity.
3Stability of the object's composition
If sipes are added to tread portions to improve steering stability, then braking performance on wet road surfaces deteriorates
Solution Approach 1:
The patent segments the sipe configuration by location, placing axial sipes primarily in the shoulder land portions rather than uniformly across the entire tread. This segmentation allows sipes to contribute to steering stability in regions where they are most beneficial while maintaining adequate groove volume in braking-critical areas for wet road performance.
Solution Approach 2:
The patent applies local quality by differentiating sipe density and configuration between shoulder land portions and center land portion. The shoulder regions have axial sipes that enhance steering stability without significantly impacting wet braking, while the center region has a different configuration optimized for maintaining both steering stability and braking performance.
4Stability of the object's composition
If the contact area is increased to improve steering stability, then braking performance on wet road surfaces deteriorates
Solution Approach 1:
The patent applies local quality by creating different contact area characteristics in different tread regions. The shoulder land portions have lateral grooves that reduce contact area locally to improve wet braking performance, while the center land portion maintains larger contact area for steering stability. This localized differentiation allows the overall tire to achieve both performance requirements simultaneously.
Data Source
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AI summary
Provided is a pneumatic tire that enables steering stability and braking performance on a dry road surface and a wet road surface to be enhanced in a balanced manner. The pneumatic tire includes a tread portion which has at least three circumferential main grooves extending in a tire circumferential direction, and at least four land portions separated by the circumferential main grooves and including shoulder land portions provided on outermost sides in a tire axial direction. At least one of the shoulder land portions has shoulder lateral grooves extending in the tire axial direction, and, as necessary, axial sipes extending in the tire axial direction. Within a tread ground-contact surface, a length in the tire axial direction of each of the shoulder lateral grooves is 10 to 30% of a tread width, and the following formula (I) is satisfied: 0 ≤ a total length in the tire axial direction of the axial sipes/a total length in the tire axial direction of the shoulder lateral grooves ≤ 0.2 (I). A rubber composition forming each shoulder land portion contains not less than 10 parts by mass of carbon black and not less than 90 parts by mass of silica, per 100 parts by mass of a rubber component.