Pneumatic Tire Tread with Shallow Grooves for Off-Road Grip
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Solution Overview
Problem
Pneumatic tires face challenges in maintaining wear resistance and steering stability on paved roads while providing enhanced driving performance on unpaved roads, particularly rocky areas, due to the trade-off between traction characteristics and rigidity.
Innovation Solution
A pneumatic tire design featuring a tread portion with longitudinal and lateral grooves, shallow grooves with bend points and sipes, and center shallow grooves with terminating ends, optimizing the groove area ratio and bend points to enhance traction and maintain block rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the groove area is made large and many edge components are provided to enhance biting into mud or the like, then traction performance on unpaved roads is improved, but block rigidity is reduced, leading to degraded wear resistance and steering stability on paved roads
Solution Approach 1:
The invention segments the groove structure into two distinct types: conventional deep grooves (longitudinal and lateral) and shallow grooves with sipes. The shallow grooves are further segmented into multiple small edge components within each block, creating numerous biting edges without significantly increasing the overall groove area. This segmentation allows the tire to achieve improved traction performance through increased edge components while maintaining block rigidity by limiting the groove depth and area of shallow grooves to 0.5-2.0mm depth and 5-20% area ratio.
Solution Approach 2:
The invention applies different groove qualities to different regions and functions: deep longitudinal and lateral grooves provide structural definition and water evacuation, while shallow grooves with sipes provide localized traction enhancement. The shallow grooves are strategically positioned in specific blocks (e.g., center blocks, intermediate blocks) rather than uniformly across all blocks, creating local quality variations that optimize both traction and rigidity in different tire regions.
2Reliability
If sipes are provided in each block to increase the number of edge components, then adherence to the road surface is enhanced, but block rigidity is reduced, making it difficult to maintain wear resistance and steering stability on paved roads
Solution Approach 1:
The invention applies partial action by providing sipes only in specific blocks (such as center blocks and intermediate blocks) rather than in all blocks across the tread. The sipe density and depth are controlled to provide sufficient edge components for adherence enhancement while avoiding excessive siping that would compromise block rigidity. The sipe dimensions are limited (depth 0.1-1.0mm, width 0.5-2.0mm) to achieve the desired effect without over-penetrating the block structure.
3Reliability
If the groove area ratio is increased to provide sufficient biting into stones and rocks, then driving performance on rocky areas is improved, but wear resistance and steering stability on paved roads deteriorate
Solution Approach 1:
The invention changes the groove depth parameter from deep (conventional grooves) to shallow (0.5-2.0mm depth), and changes the groove area ratio parameter to a specific range (5-20%). These parameter changes create numerous edge components for biting into rocks and stones while maintaining sufficient block mass and rigidity for wear resistance and steering stability on paved roads. The shallow groove depth specifically prevents excessive material removal that would compromise durability.
Data Source
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AI summary
A pneumatic tire is provided that is suitable as a tire for driving on unpaved roads and that provides enhanced driving performance, wear resistance performance, and steering stability performance on unpaved roads. A tread portion (1) includes shallow grooves (20) formed in a road contact surface of each of shoulder blocks (13s), intermediate blocks (13m), and center blocks (13c), defined by a plurality of longitudinal grooves (11) extending in a tire circumferential direction and a plurality of lateral grooves (12) extending in a tire lateral direction, the shallow groove (20) having a smaller groove depth than the longitudinal groove (11) and the lateral groove (12). The shallow groove (20) extends along the tire lateral direction, and at least one end thereof communicates with the longitudinal groove (11) or the lateral groove (12). A contour line of the shallow groove (20) is provided with at least one bend point P. A sipe (30) is provided in a flat bottom surface of the shallow groove (20) extending along the shallow groove (20). Among the shallow grooves (20), center shallow grooves (21) formed in the center block (13c) are each provided with a terminating end portion T terminating in the center block (13c).