Tire Tread Groove Geometry and Rubber Composition for Braking Stability
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Solution Overview
Problem
Tires with existing tread rubber compositions face challenges in achieving improved braking performance on dry and wet road surfaces while maintaining steering stability, particularly on slippery surfaces like manholes, and there is a trade-off between braking performance and steering stability due to variations in tire temperature.
Innovation Solution
A tire with a tread formed by a rubber composition having specific physical properties, including a tan δ at 0° C. of 0.25 to 0.55 and a dynamic storage modulus of 4 MPa to 20 MPa at 1% dynamic strain, featuring circumferential grooves with a cross-sectional area of 10 mm² or more and a groove width at the 95% groove depth position between 25% to 60% of the groove width at the tread surface, along with a specific groove width distribution to enhance land portion rigidity and drainage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubber composition is optimized for braking performance by adjusting loss properties at low and high temperatures, then braking performance on dry and wet road surfaces is improved, but the rigidity of the tread deteriorates, leading to deterioration of steering stability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the tan δ values at different temperatures (0°C: 0.25-0.55, 30°C: 0.15-0.35, 60°C: 0.18-0.38) and the dynamic storage modulus (4-20 MPa at 0°C, 1% strain). These parameter specifications allow the rubber composition to achieve both improved braking performance through optimized loss properties and maintained tread rigidity through controlled storage modulus, thereby resolving the contradiction between braking performance and steering stability.
2Stability of the object's composition
If the groove width at the 95% groove depth position is reduced to improve land portion rigidity, then steering stability is improved, but drainage performance may deteriorate
Solution Approach 1:
The patent applies local quality by creating different groove width characteristics at different depths. Specifically, the groove width Lb at the 95% groove depth position is set to 25%-60% of the groove width Lt on the tread surface, making the groove narrower at depth while maintaining adequate width at the surface for drainage. This localized differentiation allows the groove to provide both improved land portion rigidity (narrower at depth) and maintained drainage performance (adequate width at surface).
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
The tire achieves excellent braking performance on both dry and wet surfaces and maintains excellent steering stability by optimizing tread rigidity and drainage performance through the specified groove configurations and rubber composition.
Implementation Method 1
a tan δ at 0° C. being 0.25 to 0.55, a difference between a tan δ at 30° C. and a tan δ at 60° C. being −0.02 to 0.07
Implementation Method 2
a dynamic storage modulus at a dynamic strain of 1% and 0° C. being 4 MPa to 20 MPa
Implementation Method 3
by setting within a specific range a tire widthwise cross-sectional area of circumferential main grooves extending continuously in a tire circumferential direction
Implementation Method 4
by setting to a small value a groove width Lb at a 95% groove depth position with a groove depth of a groove bottom as 100% of at least a circumferential groove located on an outermost side
Data Source
AI summary
This disclosure aims to provide a tire having excellent braking performance on dry road surface and on wet road surface, and having excellent steering stability. This disclosure is a tire comprising a tread 10, wherein: the tread 10 has a plurality of circumferential grooves extending continuously in a tire circumferential direction C, the circumferential grooves including circumferential main grooves 21a, 21b, 22 with a cross-sectional area in a tire width direction W of 10 mm2 or more, and a groove width Lb at a 95% groove depth position with a groove depth of a groove bottom as 100% of at least the circumferential groove 21a located on an outermost side when mounted to a vehicle among the circumferential main grooves 21a, 21b, 22 being 25% to 60% with respect to a groove width Lt on a tread surface.