When we discuss about a motorcycle's performance, we generally speak about its engine power, torque, top speed, how fast it can accelerate, vehicle sound etc. Nevertheless, all these are meaningless if a driver cannot control the machine and/or is not comfortable while riding. There comes the importance of tyres. Tyres are the most crucial parts of a vehicle suspension system.  Tyres are the only component in a motorcycle that constantly stays in contact with the road. The part of tread which is in contact with road surface is called ‘contact patch’ & Is about half the size of a post card.  The overall suspension system (including tyres) ensures the right contact between the tires and the road surface at every stage of driving, thereby ensuring stability and good handling of the vehicle.

As tyres are the only contact with the road, they are responsible for multiple functions, such as –

Transfer the engine power to the road- meeting the demands of acceleration and braking

  Provides right hold (grip) on different surfaces like dry, wet, snow, loose soils etc.

  Helps the rider to steer the vehicle by responding to the handle movements

  Carry the weight of the vehicle & rider

 Ensuring the comfort of the rider by absorbing and dampening shock

Apart from the above aspects, tyres play a vital role in vehicle aesthetics, safety, fuel efficiency etc. These and several other challenges make Motorcycle tyre design a very interesting and responsible subject.

Apart from being a crucial part of a vehicle suspension system, tyres are the only contact between vehicle & road. Motorcycle vehicle dynamics and control characteristics are highly influenced by the tyre design. It is therefore highly imperative for a vehicle chase/suspension designer & tyre designer to work together in tandem. This will ensure that the part designs will complement each other and deliver the characteristic target performance of a motorcycle. A robust interaction mechanism between the R&Ds of OEM [Original Equipment Manufactures] and tyre manufactures is a growing necessity to cater to the ever‐increasing demands of performance entrusted upon the tyre of today. In case of tyres getting designed exclusively for aftermarket, a tyre designer work closely with the vehicle dynamics team to ensure that the retrofit design delivers desired target performance of the vehicle

Some of the major steps involved in motorcycle tyre design are

 Product planning & Tyre “Size” finalization: During this stage a vehicle designer & tyre designer jointly review the vehicle performance requirements and decides the parameters specific to tyre performance. This includes:

Defying the application /terrine: Depending on application, 2 wheelers maybe broadly classified as Sport, Cruiser, Choppers, Touring, scooter, Step through, Sport touring, Enduro etc. Different OEM’s follow different terminologies, but a for a tyre designer to understand the final use by the user is of utmost importance. Demands from a tyre varies with each vehicle category, for example, for a cruiser the tyre is designed to be robust so as to hold up the weight of such heavy bikes and deliver long tyre life, whereas for a Sport touring /super sport bike, tyres are  designed to deliver quick and precise handling with superior grip. These tires are lighter and made by using softer compounds for Superior grip.

Selection of Bias /Bias belted / Radial:   At this juncture, I am not going to delve deeper into a detailed comparison of these constructions – however, it is important to acknowledge that both these construction types have their respective advantages and disadvantages. Each of these constructions has few specific applications where one performs better than the other. The selection of construction type mainly depends on vehicle category (application), vehicle Speed, load on the tyre, stability requirements, handling requirements, etc. for example Bias tyres are used in medium speed but heavy weight vehicles owing to their sturdy sidewalls, whereas Radial tyres are the ideal choice for high speed , vehicles because of their superior dimensional stability.

Selection of Tube type Vs Tubeless:  Functionally both types of tyres have a proven track record for almost all applications. Hence this choice mainly depends on vehicle Rim design, which is decided by the overall aesthetic demand & application of the motorcycle.For high speed application, tubeless is always preferred

Finalizing the Tyre size / Tyre Geometry:  In general, we may call it as tyre “size” – which includes tyre width, tyre diameter, rim diameter etc. Tyre geometry affects the vehicle dynamics like caster, trail, vehicle Center of gravity [CoG], etc. It also influences the area of contact between vehicle and road surface under different riding conditions & load-carrying capacity of the tyres. Furthermore, tyre size significantly influences vehicle aesthetic as well.  Tyre “size” and vehicle rim size are always interconnected. Decision on one influence the decision on the other.  Usually motorcycles have different front and rear tyre sizes depending on vehicle geometry & load distribution. Tyre “sizes” are decided considering all these parameters & the designers ensures that it follows the standards’ guidelines applicable in target countries.

Tyre tread profile design:

Contrary to the passenger car tyre designs which have almost flat tread surface, motorcycle tires have a U-shaped profile and a contact patch that changes size and shape during cornering. There is a major difference in the way lateral force is built up in passenger car and two wheelers.  In case of passenger car, mechanism of lateral force builds up is due to slip angle whereas in two-wheeler it is mainly because of the camber or the leaning of the vehicle.  Hence you see a flat tread area for passenger car tyre and U-shaped profile for Motorcycle tyre

This U-shaped profile is an important design factor having a direct influence on vehicle performances such as drivability (handling) durability, ride comfort, noise and wear resistance etc.

These tread contours are designed as the arc of one radius, or a combination of arcs with two or more radii. These profiles ensure the required contact patch availability at different lean angles & are controlled by the lean characteristic of the vehicles. It is very critical to balance the performance of front tyre & rear tyre of s motorcycle for precise handling of the vehicle. The contour designs play an important role in front /Rear tyre balance.

Tyre tread pattern design:

Patterns are molded in the tread area of tyre by repeated arrangement of ‘Groves’ or ‘Blocks’ & are generally referred to as “tread pattern”.

Significance of tread pattern: 

Tread pattern plays a vital role in tyre performance such as:

Optimizing the traction on the riding surface

Eliminating aquaplaning

Optimizing the” Wear” of tread area·  

Ensuring the continuity of tyre performance at different wear Stages [ wear %] of tyre.

Rolling resistance of the tyre

Noise generation

roviding a measurable clue to the owner on time for removal /suitability for continuous usage. etc.

Tread patterns not only helps in achieving the target performance, but also impart unique look to tyres and enhance aesthetics

Tyre patterns are broadly classified into 4 Major headings

• Rib patterns
• Directional
• Block [ Knobby]
• Slick tyres [Pattern less]

Selection of which group of patterns is mainly controlled by the terrain of application, e.g. Directional patterns are preferred in paved roads and knobby pattern ae mainly used on off-road applications. Pattern less tyres are normally used in racing track applications to provide maximum traction.  Vehicles are designed to work in a combination of different terrains – similarly, tread patterns also have subgroups– which are optimized to operate in different combination of terrains. E.g. Semi knobby patterns for on – off allocations, High land – minimum grove patterns for Supersport highway applications etc.

Designer alter the direction of the grove, depth of the grove, number of groves, the ratio between Grove area & non grove area [ Land- sea ratio] , shape of the grove, the width of the grove etc. to optimize the performance of tread pattern. These patterns are designed to perform under different dynamic conditions. Nowadays designers seek the help of computer-aided simulations to predict the performance under different loading /riding conditions to optimize the pattern design.

Tyre as an Aesthetic component

The visual appeal of tyre is significant contributor in the overall aesthetics of a motorcycle. Hence in addition to performing all the functional requirements discussed so far, tyres ought to look good too.

The tread pattern should complement the overall styling language of a motorcycle. This attracts the attention of OEM’s vehicle styling studios towards tyre tread designs as well. In fact, most of the new tyre designs are done first at styling studio and then technically optimized by the tyre engineer to guarantee the functionality.

Material design

Tyre is a composite material made of different rubber compounds and reinforcing materials. Right compound and reinforcing material selection are crucial to achieve the target performance of tyre.

• Reinforcing materials:

Reinforcing materials provides the required strength and stiffness for tyre body [carcass]. This includes “tyre cords” used in tyre body ply & “bead wires” used in bead construction of tyres. Most used tyre cord materials are Nylon 6, Nylon 6-6, Polyester, Aramid, Rayon, Steel, etc.

These materials differ in their chemical composition, tensile strength, elongation properties, impact strength, temperature resistance, rubber adhesion, etc. Tyre engineer must choose the right tyre cords depending on the performance demands of the tyre like load carrying capacity, durability, impact resistance, drivability, speed of operations etc. Cost & availability also are few decisive parameters during selection of reinforcing materials.

Tyre Cord denier, cord style, EPI (Ends Per Inch), angle of cords and number of plies affect the strength of a tyre and are chosen based on engineering, and design criteria.

structural durability of a tyre is Primarily determined by the reinforcing material

• Rubber compound design

Each part of the tyre must dispense different functions and are thus designed with different rubber compounds like tread compound, sidewall compound, carcass compound, bead wire coat compound, etc.  Though all these compounds have their own importance, but tread compound selection is the most critical, as it has a direct impact on tyre traction, handling, wear performance, durability, rolling resistance, etc.

• • Trends of tread compound design:    

Even though smaller number of components are used in a motorcycle tyre, than as compared with passenger car tyres, but performance challenges involved in compounding are far more complex considering less area of tyre in contact with road. 3 major performance requirements in motorcycle tread compound are (1) Grip (2) Rolling resistance [fuel efficiency] and (3) Tyre life which is generally referred as the magic triangle in tyre rubber compounding. This is due to the contradictory response of these 3 performance characteristics to rubber compounding approach. For example, improvement in Grip normally comes with an increase in rolling resistance with conventional compounding as both are related to energy loss. It is always a challenge for tyre compounder to improve all three performance requirements together and this calls for the incorporation of advanced polymers and fillers.

Performance priorities for tread compound changes based on operating terrain, type of vehicle, etc. e.g. Street two-wheeler tread compound designs primarily focus on high grip and high-speed capabilities, whereas an on-off application tyre require higher cut and chunk resistance tread compound.

Demand for lower rolling resistance tyre is showing a steady increase Year-on-Year. Major divers for this growing demand are Electric vehicle introduction & increased focus on vehicle fuel efficiency, in few segments. Tread compounds are expected to deliver lower rolling resistance, without compromising the Grip – typical “magic triangle” puzzle for any tyre compounding engineer. Tyre industry can address this challenge by usage of new generation materials like SSBR, functionalized SSBR, high molecular

Design for manufacturing

For success of any product – Design & manufacturing sync is a must. While designing, to accommodate all functional requirements, a designer cannot ignore the significance of manufacturing process. Hence every tyre design is optimized to satisfy both functional & manufacturability needs. This if not done properly may result in suboptimal performance of the product,

Product Performance Testing

It’s important to review and verify the product performance before releasing it into the market. There are a set of Indoor & Outdoor tests for performance review. A few of them are listed below,

Indoor tests: High-speed drum test, Endurance test, Rolling resistance test, Force and moment testing, Stiffness test, Footprint etc.

Outdoor tests: Ride and Handling testing (track, off-road, public road etc.], Braking test [wet, dry], tyre wear test etc.

Blend of Engineering & Art

Being an integral part of vehicle suspension system & only contact point with road, a tyre plays significant role in motorcycle performance [safety, drivability etc.]. In addition to these performance parameters, tyres have significant influence on the overall styling of the vehicle. It complements the primary theme of the vehicle. A right blend of engineering and art is essential for a successful tyre design. One cannot substitute the other. Amongst different steps of tyre design like, dimension finalization, tread design & martial design etc. the most critical step is tread design (profile, pattern & compound)

Few areas designers are focusing today to  meet the near/middle future demands are

• Lowering the rolling resistance – without compromising grip
• Shortening the time to market.
• virtual simulation of tyre performance

 

References

1.  ‘’The pneumonic tyre’’, National Highway Traffic Safety Administration, Feb 2006
2. T. French, Tyre Technology, Hilger, New York, 1989.
3. Mechanics of Pneumatic Tires, S. K Clark, ed., University of Michigan, US Department of Transportation, National Highway Traffic Safety Administration, Washington, DC, 20590, 1891.

     4.  Handbook of vehicle-road interaction: vehicle dynamics, suspension design, and road damage / edited by David Cebon. p. cm. - (Advances in engineering), ISBN 9026515545

    5. “Tyre and Vehicle Dynamics” , Hans B. Pacejka,  Professor Emeritus Delft University of Technology, Consultant TNO Automotive Helmond

     The author is General Manager - Product Development,2&3-Wheeler tyres, CEAT Tyres

Al Salem Transportation & Tourism Co. (Al Salem) is reaping the benefits of Goodyear’s CheckPoint tyre monitoring technology system, which was implemented in its Dammam depot. This is a first for passenger transport companies in Saudi Arabia and builds upon the existing partnership between Al Salem Transportation & Tourism Co. (Al Salem), Goodyear and its official Saudi distributor, Al Rashed Tires.

Goodyear CheckPoint is a connected, yard-based drive-over tyre inspection system that provides fleet managers with useful information by reading vehicle data and tyre condition. Tyre pressure and tread depth examinations are time-consuming tasks that may be completed in seconds by Goodyear CheckPoint's automated system.

The system provides the ability to access data through user-friendly reports and allows Al Salem to address all their operational needs related to tyres. This decision is consistent with Al Salem's commitment to using cutting-edge technology to achieve the greatest levels of safety and efficiency, as well as the Saudi Vision 2030 aim of boosting the quality and connectedness of transportation networks.

Mustafa Alsalem, Business Development Manager, Al Salem Transportation & Tourism Co, said, "At Al Salem, our mission is to provide safe and comfortable journeys for everyone in the Kingdom. We pride ourselves on working only with industry leaders to deliver premium safety and service levels. Partnering with a leading global tyre manufacturer like Goodyear, renowned for their premium tyres and innovative digital fleet solutions, is a testament to our commitment to this mission."

Yasser Meyer, CEO, Al Rashed Tires, said, “We have a proud legacy of supporting the development of Saudi Arabia's automotive industry. Leveraging our in-depth market knowledge, we are able to localise global tyre technology, like Goodyear’s CheckPoint monitoring solutions, to empower our valued partners like Al Salem in their achievement of business goals.”

Saban Gungor, General Manager, Goodyear Middle East & Africa, said, "As a preferred fleet mobility partner, Goodyear is dedicated to delivering not only high-quality tyres but also value-added mobility solutions, like the CheckPoint tyre monitoring, to our fleet customers. We are thrilled to support Al Salem on their digitalisation journey with the adoption of this technology, setting a new benchmark for safety and operational efficiency in the Kingdom."

Vittoria, a global leader in cycling tyres and accessories, has announced opening new state-of-the-art research and development centres known as VittoriaLabs. These facilities, located in Italy and Thailand, are designed to push the boundaries of cycling technology and performance.

The VittoriaLabs will focus on developing innovative tyre and accessory solutions that enhance rider performance, safety, and sustainability. The centres will leverage advanced testing equipment and cutting-edge research methodologies to analyse and optimise product design.

“Vittoria Labs will be the engine driving our ambitions for market leadership in innovation in a future we are already shaping,” says Stijn Vriends, Chairman and CEO of Vittoria. “By combining state-of-the-art indoor and outdoor testing facilities, we can push the limits of what’s possible in cycling tyres and accessories while keeping sustainability at the core of our innovations,” adds Vanessa ten Hoff, Chief Innovation & Marketing Officer of Vittoria.

Vittoria’s investment in these facilities underscores the company’s commitment to innovation and its dedication to providing cyclists with the best possible products. By combining advanced technology with real-world testing, Vittoria aims to deliver products that meet the evolving needs of cyclists worldwide.

With the opening of the VittoriaLabs, Vittoria reinforces its position as a global leader in the cycling industry. The company’s focus on research and development, coupled with its passion for cycling, ensures that it will continue to drive innovation and set new standards in the years to come.

Webfleet, Bridgestone’s fleet management solution, has expanded its OEM.connect partner programme to include trailers. Schmitz Cargobull, a leading manufacturer of semi-trailers, is the first trailer manufacturer to join the programme.

This collaboration allows commercial fleet operators to seamlessly connect their Schmitz Cargobull trailers to the Webfleet platform through factory-fitted telematics. By eliminating the need for aftermarket hardware installations, fleet managers can save time and reduce costs.

“Trailers are the backbone of long-haul goods transportation, but managing a trailer fleet can be challenging,” says Taco van der Leij, Vice President, Webfleet Europe at Bridgestone Mobility Solutions.

“Making our proven Webfleet Trailer solution now easily accessible via OEM data, will help even more businesses with real-time data insights and actionable intelligence to maximise trailer performance. We are happy that we are collaborating with Schmitz Cargobull, offering our customers seamless integration with Europe’s leading semi-trailer manufacturer”.

Sören Danielsen, Manager, Strategy & Business Development at Schmitz Cargobull adds:  “With the TrailerConnect Data Management Center from Schmitz Cargobull, hauliers have full control over their data and can pass on selected data to third parties in an efficient way. By intelligently linking information on the vehicle, tour and order, more than just position and temperature data can be selected, processed and transmitted to third-party systems at the touch of a button in future. The TrailerConnect Data Management Center stands for connectivity and transparency. Everyone involved along the supply chain benefits from this.”

The integrated solution provides fleet operators with valuable insights into trailer performance, including location tracking, maintenance alerts and payload monitoring, said the tyre maker.

Bridgestone has joined hands with Astrobotic Technology to develop lunar rover tyres.

Bridgestone will leverage its 90 years of expertise in developing tyres for Astrobotic’s 24U CubeRover. These tyres will be designed to withstand the harsh lunar environment, including extreme temperatures and rugged terrain.

Bridgestone’s tyres will play a crucial role in enabling the rover to navigate the challenging lunar terrain.

The collaboration highlights the Japanese tyre maker’s commitment to expanding its reach into new and innovative areas of mobility. By partnering with Astrobotic, a leading space exploration company, Bridgestone aims to contribute to the advancement of lunar exploration and space technology.

The 24U CubeRover is a compact lunar rover designed to provide mobility, power and communication support for scientific instruments and payloads on the lunar surface.

As per Bridgestone, this partnership marks a significant milestone for the company as it expands its horizons beyond Earth and into the cosmos.