In vehicle dynamics, slip angle (also known as sideslip angle) is the angle between the actual direction of travel of a rolling wheel and the direction towards which it is pointing. Slip (usually described as percent slip), is the relative motion between a tyre and the road surface on which the tyre is moving on. This slip can be generated either by the tyre’s rotational speed being greater or less than the free-rolling speed, or by the tyre’s plane of rotation being at an angle to its direction of motion. Fig.1 shows a top view of how slip angle occurs when the vehicle is turning right.

It is called slip angle, because the part of the contact patch that is to the outside of your turn is moving faster than the wheel itself is in the direction it (the contact patch) is pointing , while the part on the inside is moving more slowly. Since the outside part is moving faster than the tyre it must be slipping and hence is the name of ‘Tyre Slip’. The inside part is gripping better than it would if moving in a straight line. For this reason, the contact patch ‘walks’ itself into the turn.

Mathamatical model of slip angle

The slip is generally given as a percentage of the difference between the surface speed of the wheel compared to the speed between axis and road surface. Fig.2 shows that slip angle is the vector sum of wheel forward velocity and lateral velocity. Mathematically, slip could be represented, as:

where , w is rotational speed of the wheel, r is wheel radius and v is vehicle speed. This indicates that a positive slip means the wheels are spinning and negative that they are skidding. Locked brakes, wr = 0, means that slip is -100% and spinning on the spot, v = 0 and wr ≠ 0, means that ∞.

Slip angle , therefore, is the angular difference between the direction the tyre contact patch with the road is pointing and the direction of the wheel (Fig.3). In actual case, the tyre tread does not point in the same direction as the wheel. This is because a tyre is being made of rubber, the sidewalls deform, and the tread pattern itself can ‘squirm’ when the wheel is turned from the straight-ahead.

In fact, modest slip angles are ‘good’ as tyres generate progressively more grip with increasing slip angles (Fig.3).For every type of vehicle and tyre the modest slip angle or the good slip angle is different and for all the tyres in your car, the slip angle might be different at any point of vehicle dynamics.When the limit exceeds, where after no further grip is generated. Thereafter, increasing slip angles are ‘bad’, and the tyre will tend to lose grip. Because of the slip angle, the contact patch of the tyre (Fig.3) need not be in the same orientation as the whole wheel, often lagging a few degrees behind. Greater the slip angle will obviously mean that the larger portion of the contact patch is slipping (Fig.3). At some point there is so little part of the contact patch that there is no slipping, which means that traction is lost and the tyre begins to slide. As the tread element moves through the contact patch it will be deflected further from the wheel mid-plane(Fig.3). This deflection gives rise to the slip angle, and to the cornering force.

Tyres seem to operate at their peak performance when they are under a few degrees of slip angle, they generate the most grip at that particular slip angle. For race and high performance tyres this optimum slip angle is around 6 to 10 degrees while this number is a little lower for street tyres (Fig.4).

Measurement of slip angle

There are two main ways to measure slip angle of a tyre: on a vehicle as it moves, or on a dedicated testing device. There are a number of devices which can be used to measure slip angle on a vehicle as it moves; some use optical methods, some use inertial methods, some GPS and some both GPS and inertial.

Various test machines have been developed to measure slip angle in a controlled environment. Sensors measure the force and moment generated on a dynamic vehicle, and a correction is made to account for the curvature of the track. Other devices use the inner or outer surface of rotating drums, sliding planks, conveyor belts, or a trailer that presses the test tyre to an actual road surface. These days computer simulation models are available for measuring tyre slip angle. Technicians can use a simple tyre finite element model to generate lateral, tangential and radial tyre accelerations for a fixed load and slip angle. The profiles are validated by using experimental data. The simulated acceleration profiles are used for the estimation of slip angle and tyre/road friction coefficient.

Effects of slip angle

Each tyre will have its own slip angle. A tyre that is not slipping has a slip angle of zero degrees. The ratios between the slip angles of the front and rear axles will determine the vehicle’s behavior in a given turn. If the ratio of front to rear slip angles is greater than 1:1, the vehicle will tend to understeer, while a ratio of less than 1:1 will produce oversteer (Fig.5).

Actual instantaneous slip angles depend on many factors, including the condition of the road surface, but a vehicle’s suspension (Fig.6) can be designed to promote specific dynamic characteristics. Incidentally, a vehicle suspension system may include; Coil spring, Leaf spring, Hydraulic and Air Spring or their combinations. This is very important for racing car as they need to take sharp turns on high speeds.

A principal means of adjusting developed slip angles is to alter the relative roll couple (the rate at which weight transfers from the inside to the outside wheel in a turn) front to rear by varying the relative amount of front and rear lateral load transfer. This can be achieved by modifying the height of the roll centers, or by adjusting roll stiffness, either through suspension changes or the addition of an anti-roll bar. Because of asymmetries in the side-slip along the length of the contact patch, the resultant force of this side-slip occurs away from the geometric center of the contact patch, a distance described as the pneumatic trail, and so creates a torque on the tyre.

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Pirelli is set to play a central role as the FIM Superbike World Championship concludes the first half of its season this weekend at Donington Park for the UK Round. Marking the final event before the summer break, the Italian tyre manufacturer has equipped competitors with the softest rear compounds from its 2026 standard range. This selection represents a clear advancement in development from the previous year, when riders were limited exclusively to older specification tyres.

For the premier WorldSBK class, the rear tyre allocation is headlined by the SCQ extrasoft compound, intended primarily for qualifying and the Superpole Race. This option, the softest in Pirelli’s portfolio, has already garnered positive feedback from riders during the Emilia-Romagna Round for its exceptional single-lap pace and consistent performance over a sprint distance. Complementing the SCQ are the SCX supersoft and SC0 soft compounds, while front tyre duties are covered by the standard SC1 soft and SC2 medium solutions, with the softer front being the overwhelming preference of last year’s grid, including triple race winner Toprak Razgatlıoğlu.

The notoriously unpredictable British weather remains a critical variable, with cool morning temperatures and frequent rain showers posing significant challenges for teams. Pirelli’s range has historically demonstrated considerable adaptability across fluctuating track and air temperatures, maintaining reliable grip in both cooler and warmer conditions. To address potential precipitation, the allocation is supplemented by DIABLO Wet intermediate and full DIABLO Rain tyres for both front and rear positions, ensuring competitors have viable options regardless of the elements.

In the supporting categories, WorldSSP riders will retain the SCX and SC0 rear compounds alongside the SC1 and SC2 front options. Meanwhile, the WorldWCR field and the emerging talents of the Yamaha R3 World Cup will also be in action, with both series utilising the Pirelli DIABLO Superbike SC1 tyre on both axles throughout the weekend’s racing programme.

Giorgio Barbier, Pirelli Motorcycle Racing Director, said, “Donington Park is a very distinctive circuit and, in many respects, a unique venue on the FIM Superbike World Championship calendar. The opening part of the lap features a series of fast, flowing corners taken at high speed and rapid changes of direction that require riders to manage significant power while the bike is still heavily leaned over. This demands tyres capable of delivering outstanding grip, precision and stability while maintaining consistent performance over race distance.

"Compared with last year, when only standard range solutions were available and no development specifications were included, this season, while confirming the same compounds introduced in 2025, we will provide riders with the complete 2026 standard range. The SCQ extrasoft compound will be the softest option in the allocation and can be used not only in free practice and qualifying but also, potentially, in the Superpole Race. For the longer races, riders will be able to rely on the SCX supersoft and, should temperatures be lower, the SC0 soft compound – solutions that have already demonstrated throughout the season an excellent balance between outright performance and consistency, as reflected by the many new records that have been set.

"Finally, the weather, which has historically been unpredictable in the UK, will once again be a key factor. Rain and low temperatures, even in the middle of summer, can have a major influence on tyre management and race strategies. Having a complete and versatile range available will therefore be essential to provide the best possible support in any weather conditions.”

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Sri Trang Group has unveiled a comprehensive organisational strategy centred on its ‘Empowering AI’ mission, designed to integrate artificial intelligence across its operations to boost efficiency and foster long-term sustainability. The initiative was formally announced during the company’s flagship annual gathering, the Sri Trang Town Hall 2026, held at the Four Points by Sheraton Phuket Patong Beach Resort. The event drew over 1,700 participants, including executives such as the Chairman, Group CEO and other board members, alongside employees from domestic and international branches who attended both in person and virtually.

Central to the new vision is the Group’s commitment to leveraging AI and data analytics throughout its entire value chain, supported by a robust Enterprise Data Foundation and an AI Governance framework. These systems are intended to ensure meticulous data management and foster stakeholder confidence. The application of AI is being tailored to optimise specific operational phases, from upstream procurement and production to downstream sales and logistics, aiming for precision in market forecasting, quality control and customer responsiveness.

Parallel to its technological push, Sri Trang is prioritising the development of AI Agents and practical AI Use Cases to accelerate tangible business outcomes. This effort is complemented by a cultural shift towards an ‘AI x Human’ paradigm, preparing the workforce to collaborate effectively with intelligent systems. Concurrently, the Group is reinforcing its dedication to environmental, social and governance principles, focusing on resource efficiency and the management of energy, water, waste and emissions as part of its trajectory towards a Net Zero target.

To support its ESG goals, Sri Trang is enhancing data systems to align with international standards like ISO 14064-1, ensuring accuracy and auditability for better risk management and decision-making. The company is also expanding collaboration with suppliers through its ESG Partner approach to elevate industry standards. This strategic direction underscores Sri Trang Group’s ambition to solidify its status as an innovation-led entity, combining human potential with AI to drive the Thai natural rubber sector towards resilient and sustainable growth on the world stage.

Dr Viyavood Sincharoenkul, Chairman of Sri Trang Group, delivered a keynote address on the vision, stating, “AI will not merely be a tool; it will become part of Sri Trang’s way of working and decision-making. We are building the Sri Trang AI Factory to connect data, technology and people together. AI is not simply a new technology but a major transformation in the way we work and compete in business. As the world accelerates AI adoption, organisations and people that are able to learn, adapt and work effectively with AI will be the ones that gain a competitive advantage and achieve sustainable growth in the future. Our goal is not to have the best AI but to build an organisation where everyone can use AI effectively, supported by trusted data, proper governance and a culture of continuous learning. The success of AI is not measured by the number of systems developed but by the number of people who can work effectively with AI and create value for the organisation.”

Veerasith Sinchareonkul, Group CEO, Sri Trang Group said, “The ‘AI Revolution Without Boundaries’ does not mean bringing in technology to replace our people. Rather, it means using AI to enhance people’s capabilities so that they can work smarter, faster and more efficiently. In essence, the meaning of ‘Empowering AI’ is ‘Empowering People with AI’ empowering our people to grow and move forward through the potential of AI. We believe in the power of collaboration between humans and AI. When AI works alongside people at every level, it helps improve decision-making accuracy, enhance the efficiency of frontline employees, strengthen executive leadership and foster a culture of continuous learning, teamwork and innovation. The future of the organisation is therefore not one in which AI replaces humans, but one in which humans grow together with AI without limits.”

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Michelin has expanded its retail footprint in North India by inaugurating two Michelin Tyres & Services (MTS) outlets, located in Amritsar and Panchkula. The Amritsar location operates through a partnership with National Auto, while the Panchkula facility is a collaboration with Universal Tyres. This development underscores the French tyre giant’s strategy to place its globally recognised products and services within closer reach of consumers in a rapidly developing automotive market.

Each of the new establishments spans 5,000 square feet, situated strategically on Loharka Road and within Panchkula’s Industrial Area. Designed as modern service hubs, they provide a full spectrum of offerings, ranging from passenger car and two-wheeler tyres to advanced wheel alignment and mechanical maintenance. The stores stock renowned product lines such as the Primacy, Pilot Sport and Latitude Sport series, aiming to deliver a premium and seamless experience for vehicle owners.

The selection of Amritsar and Panchkula reflects Michelin’s assessment of their growth potential, driven by tourism, infrastructure projects and a rising number of private vehicle owners. To capitalise on these opportunities, Michelin has aligned with established regional players. National Auto, a trusted entity in Amritsar since 1927, brings a long-standing reputation for quality service, while Universal Tyres contributes over three decades of technical expertise and market knowledge in the Panchkula region.

These partnerships are central to Michelin’s broader objective of delivering superior mobility solutions rooted in safety and durability. By combining its own technological leadership with the local acumen of its partners, the company aims to strengthen its service ecosystem and cater to the evolving demands of the northern Indian automotive sector.

Shantanu Deshpande, Managing Director, Michelin India, said, “North India continues to be a key market in Michelin's growth journey, supported by rising vehicle ownership, improving road infrastructure and growing demand for premium mobility solutions. The launch of our new Michelin Tyres & Services Stores in Amritsar and Panchkula marks another important step in strengthening our retail presence and bringing Michelin's globally benchmarked products and services closer to customers across the region. As we prepare to introduce Made-in-India passenger car tyres, we remain focused on delivering solutions tailored to the evolving needs of Indian consumers.”

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Tyres Europe has issued a formal call for the Industrial Accelerator Act to be revised, urging policymakers to grant greater recognition to the tyre sector’s strategic importance within the continent’s automotive ecosystem. In a newly published position paper, the organisation argues that the current framework insufficiently addresses the industry’s unique contributions and challenges.

The association is advocating for several key amendments, including an expanded scope that acknowledges tyres as critical components in both the replacement and original equipment markets, thereby stimulating demand for EU-manufactured products. Additionally, Tyres Europe proposes the establishment of a Union origin definition that would prioritise European production in public procurement and state-aid schemes. The paper also highlights tyres’ potential to enhance energy efficiency and lower CO2 emissions for light vehicles, while calling for dedicated backing for retreaded and EU-made truck and bus tyres, alongside increased financial mechanisms for industrial decarbonisation and improved governance of manufacturing acceleration zones.

With these targeted modifications, Tyres Europe contends that the Industrial Accelerator Act could effectively foster a market for low-carbon, high-performance tyres produced domestically. Such adjustments would simultaneously bolster competitiveness, support decarbonisation goals and reinforce the overall resilience of Europe’s automotive supply chain.

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