Racing Kart Tire Tread Block Geometry for Wet Grip

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Solution Overview

Problem

Racing kart tires experience inferior traction, braking, and cornering performance on wet roads due to reduced ground contact area and increased camber angle during cornering, which is exacerbated by the lack of a suspension mechanism.

Innovation Solution

A racing kart tire design with a tread portion featuring blocks divided by grooves of specific widths and configurations, including a center longitudinal groove and transverse grooves, which allows for effective drainage and increased ground contact by utilizing the edges of blocks to improve performance under wet conditions, even when the camber angle changes during cornering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a rain tire with tread grooves is used to improve wet road drainage, then drainage performance is improved, but ground contact area is reduced leading to inferior traction and braking performance

Engineering Contradiction:
Improvedrainage performanceVSAvoidground contact area
Core Design Contradiction:
Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent applies local quality by creating three distinct block types with different ground contact surface areas: center blocks (largest area for straight-line traction), middle blocks (intermediate area for transition zones), and shoulder blocks (smallest area for cornering). This localized differentiation allows each region to optimize its function while maintaining overall wet road performance through the groove system.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If the ground contacting camber angle increases during cornering without suspension, then cornering capability is improved, but ground contact area is further reduced worsening traction and braking performance

Engineering Contradiction:
Improvecornering capabilityVSAvoidground contact area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent implements dynamics by designing a tread pattern that automatically adapts to changing camber angles during cornering. The progressive reduction in block surface area from center to shoulder blocks, combined with the groove configuration, allows the contact patch to dynamically shift and maintain optimal ground contact as the camber angle changes, preserving traction and braking performance throughout the maneuver.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If groove widths are increased to improve drainage, then drainage performance is improved, but block contact area is reduced affecting traction performance

Engineering Contradiction:
Improvedrainage performanceVSAvoidblock contact area
Core Design Contradiction:
Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent applies parameter changes by optimizing groove widths to specific ranges (3-20mm for longitudinal grooves, 2-10mm for transverse grooves) that balance drainage capability with block contact area preservation. This parameter optimization ensures sufficient water evacuation while maintaining adequate rubber-to-road contact for traction.

Inventive Principle:
Principle #35Parameter changes

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 high levels of traction, braking, and cornering performance on wet roads by maintaining ground contact through the middle blocks during cornering and center blocks during straight running, without sacrificing performance and without the need for sipes, thus preventing uneven wear.

Implementation Method 1

since the grooves such as longitudinal grooves and transverse grooves which divide the blocks have widths of 3 to 20 mm, sufficient drainage is secured

Methodology Applied
Scientific EffectDrainage:

Implementation Method 2

the edges of the blocks are effectively utilized to improve the traction performance, braking performance and cornering performance under wet road conditions

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

the tread portion can be easily bent in the vicinity of the middle blocks, and thereby the ground contact during cornering is increased

Methodology Applied
Scientific EffectElastic deformation: Deformation

Data Source

PatentEP2457746B1Racing kart tire
Publication Date: 2013.09.04 SUMITOMO RUBBER INDUSTRIES LTD
  • EP2457746B1 patent drawingFigure 1
  • EP2457746B1 patent drawingFigure 2
  • EP2457746B1 patent drawingFigure 3

AI summary

A racing kart tire (1) having a diameter of not more than 300 mm comprises a tread portion (2) provided with blocks (5) divided by tread grooves (3,4) having widths of 3 to 20 mm. The grooves include a center longitudinal groove (3A). The blocks on each side of the tire equator include a row of center blocks (5A), a row of middle blocks (5B) and a row of shoulder blocks (5C). The ground contact area (5Bt) of the middle block is less than that (5At) of the center block and also less than that (5Ct) of the shoulder block.