Off-road Motorcycle Tire Shoulder Block Swelling Design
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Solution Overview
Problem
Off-road motorcycle tires face challenges in enhancing cornering performance and lateral grip without increasing tread width, which can lead to interference with the swing arm or driving chain and reduce block strength, causing chipping or damage.
Innovation Solution
Incorporating a swelling portion on the lateral face of the shoulder block that extends outward beyond a reference line, maintaining block strength while allowing the inner edge of the tread face to be positioned further outward without increasing tread width, and optimizing the radial height and swelling dimensions to enhance cornering performance and prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the axially inner block edge of the shoulder block is provided axially outward to enhance lateral grip and cornering performance, then the lateral edge effect is enhanced and cornering speed is increased, but the tread width is naturally increased causing interference with swing arm and/or driving chain
Solution Approach 1:
The invention introduces a swelling portion that protrudes in the radial direction from the lateral face of the shoulder block. This adds a third dimension (radial protrusion) to the block structure, allowing the axially inner block edge to be positioned axially outward without increasing the axial tread width, thereby resolving the contradiction between lateral grip enhancement and interference prevention
Solution Approach 2:
The swelling portion is localized specifically on the lateral face of the shoulder block, creating a local structural enhancement. This allows the shoulder block to have different effective widths at different locations: the axially inner edge is outward for lateral grip, while the overall tread width remains controlled to prevent interference
2Reliability
If the axially inner block edge of the shoulder block is shifted outward while maintaining tread width, then lateral grip is improved, but the block width of the shoulder block is reduced causing chipping and/or damage
Solution Approach 1:
The swelling portion adds radial depth to the shoulder block structure. This radial extension compensates for the reduced axial block width, maintaining sufficient block volume and structural integrity to prevent chipping and damage while allowing the axially inner edge to be positioned outward for improved lateral grip
Solution Approach 2:
The swelling portion creates a composite cross-sectional shape in the shoulder block, combining axial width and radial depth. This composite geometry maintains the necessary material volume and structural strength despite the reduced axial block width, preventing block damage while enabling improved cornering performance
Data Source
AI summary
An off-road tire for motorcycle comprises a tread portion provided with a plurality of blocks including an axially outmost shoulder block, a pair of sidewall portions, and a pair of bead portions, the shoulder block comprising a tread face with an axially outer edge corresponding to a tread edge and a lateral face extending from the tread edge to an radially inner edge located on the sidewall portion, the lateral face with a swelling portion swelling axially outside of the tire than a reference line which connects the tread edge and the radially inner edge, in a cross section including a tire axis, and the radial height of the radially inner edge of the lateral face from the bead base line being in a range of from 30 to 50% of the tire section height.