Asymmetric Tire Tread Profile Stiffness Design
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Solution Overview
Problem
Pneumatic vehicle tires face challenges in achieving balanced transverse and circumferential stiffness for improved cornering, responsiveness, and uniform tread wear, especially on icy surfaces, due to varying ground pressure distribution caused by differing stiffness in profile positives.
Innovation Solution
The tire design features profile positives in the inner tread area with a transverse stiffness at least 10% lower and circumferential stiffness at least 15% greater than those in the outer area, with a larger positive proportion in the inner area to enhance grip and responsiveness, while maintaining uniform wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the transverse rigidity of profile positives in the outer tread area is increased to improve driving properties on dry road surfaces during cornering, then cornering performance is improved, but the circumferential rigidity of profile positives in the inner tread area decreases, reducing responsiveness at low steering angles
Solution Approach 1:
The patent applies different rigidity characteristics to different regions of the tread. Specifically, the outer tread area (shoulder-side peripheral area in the outer area) is designed with higher transverse rigidity to improve cornering performance, while the inner tread area (shoulder-side peripheral area in the inner area) is designed with higher circumferential rigidity to maintain responsiveness at low steering angles. This regional differentiation of mechanical properties resolves the contradiction by optimizing each area for its specific functional requirement.
Solution Approach 2:
The patent employs an asymmetrical tread design where the profile positives in the outer and inner tread areas have deliberately different stiffness characteristics. The outer area profile positives have higher transverse rigidity while the inner area profile positives have higher circumferential rigidity. This asymmetrical distribution of mechanical properties allows the tire to simultaneously achieve good cornering performance and low-steering-angle responsiveness, which would be impossible with a symmetrical design.
2Stability of the object's composition
If the total number of incisions per profile positive is increased to make the tread strip stiffer overall, then uniform wear is ensured, but the ground pressure distribution becomes uneven, reducing grip on icy ground
Solution Approach 1:
The patent optimizes the incision configuration differently for profile positives in the outer and inner tread areas. In the outer tread area, the incisions are arranged to achieve a stiffness that promotes even wear while maintaining adequate ground contact. In the inner tread area, the incisions are configured to preserve larger contact areas for better grip on icy surfaces. This localized optimization of incision patterns allows the tread to achieve both uniform wear and reliable grip on icy ground.
Solution Approach 2:
The patent varies key parameters of the incisions including their number, depth, spacing, and orientation across different regions of the tread. By adjusting these parameters locally rather than uniformly across the entire tread, the patent achieves an optimal balance between tread stiffness for even wear and sufficient ground contact pressure for grip on icy surfaces. The parameter changes are tailored to the specific functional requirements of each tread region.
Data Source
Figure 1
Figure 2~4
AI summary
The vehicle tire has a tread strip with three peripheral regions (U1 to U4) of certain width of profile positives. The profile positives are provided with multiple slots (18,19,20) that run parallel to each other in the circumferential direction. The profile positives in the shoulder sided peripheral region in an inner region (I) of the tread strip has a lower transverse rigidity of about 10 percent and a higher circumferential rigidity of about 15 percent than the profile positives in the shoulder sided peripheral region in an outer region (A) of the tread strip.