Pneumatic Tire Tread Layout for Stable Handling and Durability
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Solution Overview
Problem
Conventional pneumatic tires exhibit significant changes in handling characteristics between low-speed and high-speed running, and have insufficient durability.
Innovation Solution
A pneumatic tire design featuring a rubber composition with a loss tangent of 0.25 or less, circumferential grooves forming rib-shaped land portions, and specific geometric constraints such as cross-sectional width, outer diameter, and virtual volume ratios, along with an aspect ratio of 40% or more, to reduce rolling resistance and suppress handling characteristic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rubber composition formulation is optimized to reduce rolling resistance, then fuel efficiency is improved, but handling characteristics change significantly between low-speed and high-speed running
Solution Approach 1:
The patent applies parameter changes by precisely controlling the loss tangent of the rubber composition at 15°C to be 0.25 or less, while also controlling the ratio of ground contact areas (Sa/Sb) to be within 0.60 to 0.95. These parameter optimizations enable the tire to maintain consistent handling characteristics across different speeds while achieving low rolling resistance through reduced heat generation.
2Loss of energy
If the rubber composition is modified to reduce rolling resistance, then fuel efficiency improves, but tire durability is insufficient
Solution Approach 1:
The patent resolves this contradiction by optimizing multiple parameters simultaneously: the loss tangent at 15°C is controlled to be 0.25 or less to reduce heat generation and improve durability, while the ground contact area ratio (Sa/Sb) is controlled within 0.60 to 0.95 to ensure uniform pressure distribution. This combination of parameter optimizations achieves both low rolling resistance and sufficient durability.
3Reliability
If the tire geometry is adjusted to improve ground contact uniformity, then handling characteristics are improved, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry by intentionally creating an asymmetric ground contact pattern through circumferential grooves, where the ground contact area on one side (Sa) is deliberately made different from the other side (Sb). The ratio Sa/Sb is controlled to be within 0.60 to 0.95, creating an asymmetric pressure distribution that improves handling characteristics while maintaining a relatively simple tire structure without requiring complex additional components.
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 reduced rolling resistance and improved durability by minimizing heat generation and uniform ground contact pressure, maintaining consistent handling characteristics across speed ranges.
Implementation Method 1
a rubber layer constituting a tread portion formed by a rubber composition having a loss tangent (15° C. tan δ) of 0.25 or less measured under conditions of 15° C., frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%
Data Source
AI summary
Provided is a pneumatic tire having a sufficiently suppressed change in handling property and sufficiently improved durability. This pneumatic tire comprises a tread portion including a rubber layer, the rubber layer is formed of a rubber composition having 0.25 or less of a loss tangent (15° C. tan δ) measured under such conditions as 15° C., frequency 10 Hz, initial strain 5%, and dynamic strain rate 1%, the tread portion includes a plurality of rib-like land portions formed by circumferential grooves continuously extending in the circumferential direction, the tread portion has a ground contact surface partitioned, at the equatorial plane, such that one ground contact area Sa and the other ground contact area Sb satisfy a relationship of Sa>Sb, and (formula 1) and (formula 2) are satisfied where Wt (mm) is the cross sectional width of the tire, Dt (mm) is the outer diameter, and V (mm3) is a virtual volume being the volume of a space occupied by the tire when the tire is mounted on a standard rim and the internal pressure is 250 kPa.1600≤(Dt2×π/4)/Wt≤2827.4 (formula 1)[(V+1.5×107)/Wt]≤2.88×105 (formula 2)