Snow Tire Tread Composition for Lightweight Steering Stability
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Solution Overview
Problem
Tires with thin rubber thickness face decreased steering stability on snowy road surfaces due to easy cooling of the rubber surface, leading to reduced followability and increased concern for steering stability.
Innovation Solution
A tire design with a specific tread pattern featuring circumferential grooves, lateral grooves, and a rubber composition with a glass transition temperature between -40°C and -15°C, a total styrene amount less than 20% by mass, and a lateral groove area ratio between 10% and 40%, which enhances heat generation and surface deformation, improving followability and steering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the rubber thickness is reduced to decrease tire weight, then fuel efficiency is improved, but the rubber surface is easily cooled in low temperature environment, causing decreased followability and steering stability on snowy road surfaces
Solution Approach 1:
The patent changes the glass transition temperature parameter of the rubber composition to a specific range (-50°C to -30°C) and controls the styrene content parameter (10% to 20% by mass). These parameter changes enable the rubber to maintain appropriate flexibility and heat generation characteristics in cold environments, preventing the rubber surface from being easily cooled while keeping the tire weight reduced.
Solution Approach 2:
The patent uses a composite rubber composition comprising multiple rubber components (natural rubber, styrene-butadiene rubber, polybutadiene rubber) with specific proportions, along with controlled styrene content and glass transition temperature. This composite material structure provides both the weight reduction benefits and the cold-weather performance needed for steering stability on snowy surfaces.
2Weight of moving object
If the rubber thickness is reduced to decrease tire weight, then fuel efficiency is improved, but the heat generation capability decreases, leading to reduced followability on cold road surfaces
Solution Approach 1:
The patent optimizes the glass transition temperature parameter to -50°C to -30°C, which directly affects the rubber's molecular mobility and heat generation characteristics. This parameter change ensures that the rubber can generate sufficient heat through deformation in cold environments, preventing the rubber surface temperature from dropping too low, while maintaining reduced tire weight.
Solution Approach 2:
The patent applies local quality by controlling the styrene content distribution (10% to 20% by mass) within the rubber composition. The styrene component specifically influences the rubber's glass transition temperature and heat generation properties, providing localized thermal characteristics that improve followability on cold surfaces without compromising overall weight reduction.
3Ease of manufacture
If the styrene amount is increased to improve rubber properties, then processing and performance are enhanced, but the glass transition temperature shifts, causing decreased followability in low temperature environments
Solution Approach 1:
The patent precisely controls the styrene content parameter within 10% to 20% by mass and the glass transition temperature within -50°C to -30°C. This parameter optimization balances the processing benefits of styrene (improved processability and rubber properties) with the need for low-temperature followability, preventing excessive cooling of the rubber surface in snowy conditions.
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 improved steering stability on snowy road surfaces while maintaining reduced weight relative to maximum load capacity, ensuring excellent fuel efficiency and enhanced traction.
Implementation Method 1
when the rubber surface is cooled, followability to the road surface decreases
Implementation Method 2
Heat generation becomes high even in the low temperature environment
Implementation Method 3
setting a glass transition temperature (Tg) of a rubber composition of the tread part within a predetermined range
Data Source
Figure 1~2
Figure 3
AI summary
The present invention provides a tire having improved steering stability on a snowy road surface even when the tire weight with respect to the maximum load capacity is reduced. Provided is a tire comprising a tread part, the tread part having a tread end (To) placed outside a vehicle and a tread end (Ti) placed inside the vehicle when mounted on the vehicle, and having one or more circumferential grooves (11, 12) extending continuously in a tire circumferential direction and two or more land parts (30, 40) partitioned by the circumferential grooves between the tread end To and the tread end Ti, the land part having a plurality of lateral grooves (20, 21) extending in a tire width direction, the tread part comprising a rubber composition having a glass transition temperature (Tg) of -40°C to -15°C, the rubber composition comprising a rubber component having a total styrene amount of less than 20.0% by mass in the rubber component, wherein a lateral groove area ratio R of at least one land part of the land parts satisfies the condition (1): 10%≤R≤40%, and wherein a weight WT (kg) and the maximum load capacity WL (kg) of the tire satisfy the condition (2): WT/WL≤0.015.