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.

Leading data and analytics company GlobalData has predicted substantial ripples across the global automotive industry owing to US Government’s announcement of 25 percent tariff on all foreign automobiles and automotive parts entering the country. Though President Donald Trump has since announced a 90-day suspension on the new tariff implementation to allow trade negotiations with partner trading countries, the report says that the situation still poses a significant challenge for the global automotive industry.

According to Madhuchhanda Palit, Automotive Analyst at GlobalData: “The economic repercussions of these tariffs are particularly pronounced for Japan, where the automotive industry is a vital economic pillar. According to the Japan Automobile Manufacturers Association (JAMA), over 30 percent of Japanese car exports were directed to the US in 2023, solidifying its status as the largest single-country export market. Projections from Japan’s Ministry of Finance indicate that automotive sales accounted for approximately 30 percent of Japan's total exports to the US, valued at around JPY 6 trillion (USD 40 billion) in 2024. The looming tariffs threaten to disrupt this critical trade, compelling the Japanese government to act swiftly to negotiate favourable terms with US officials.”

South Korea too has implemented emergency steps to offset the expected financial impact of US tariffs. With plans to increase policy financing support to local manufacturers to KRW 15 trillion (roughly USD 10.09 billion) by 2025, the South Korean trade ministry has unveiled a multibillion-dollar support package that includes tax breaks, subsidies and increased financial backing for regional automakers. India is positioned to be impacted by the new tariff laws as a major supplier of automobile components to the United States. The 90-day negotiating pause is an important window of time for APAC nations to adjust to the changing nature of trade, notes the report.

The report adds that German manufacturers are expected to suffer the most as a result of the US tariffs on exports from the EU automobile sector. Prominent companies like Mercedes, Audi, BMW and Volkswagen now have to make difficult choices about whether to stop shipments or pay the additional expenses associated with tariffs. As a result of US tariffs on EU steel and aluminium, the EU has responded by levying a 25 percent duty on a variety of US commodities worth about EUR 22 billion. However, the EU has also halted its retaliatory tariffs until the conclusion of ongoing trade talks, in response to the US president's declaration of a 90-day postponement of tariff rises.

The report notes that this tit-for-tat strategy highlights the brittleness of global trade relationships and that a protracted trade war may lead to a negative cycle of tariffs that would hurt both economies. As a result, a solution must be found to promote a more stable environment in the automotive industry. “The US president's decision to suspend tariff increases for 90 days while negotiations unfold presents a critical opportunity for all stakeholders involved. Larger manufacturers may adapt through strategic pricing and production shifts, but smaller suppliers may face a more precarious future amid these changes. As the automotive sector increasingly focuses on domestic production to mitigate tariff impacts, the evolving landscape presents both immediate challenges and potential long-term opportunities for growth and investment,” concluded Palit.

The Rubber Board has announced the commencement date for a three-month Certificate Course in molecular biology and biotechnology techniques through the National Institute for Rubber Training (NIRT). The course begins on 7 May 2025 and the number of seats is limited to 15.

Graduates, postgraduates, research scholars and practitioners interested in academic and industrial employment based on molecular biology and biotechnology in any field of biological science are encouraged to apply by 1 May 2025, according to the organisation's press release. In addition to updating knowledge, the course focuses on developing practical skills in some of the fundamental molecular procedures, such as gene cloning, sequencing, gene expression, transgenic development and the extraction of nucleic acids (DNA, RNA). According to the statement, individuals who successfully complete the course will be qualified to participate in cutting-edge research in molecular biology and related fields as a potential career opportunity.

Interested candidates may contact on 9495928077 (WhatsApp 0481 2351313) or send a mail to training@rubberboard.org.in for more details.

Nexen Tire’s N’FERA Sport R and N’Blue 4 Season 2 tyres have emerged winners at the 2025 Green Good Design Awards, the eco-focused division of the Good Design Awards, organised by The Chicago Athenaeum and The European Centre for Architecture, Art, Design and Urban Studies. Both the tyres were recognised in the Green Transportation category for their eco-friendly design.

The N’FERA Sport R, a high-performance summer tyre, was praised for its function-driven design that enhances driving performance and user convenience. The tyre features ‘Step Groove’ tread pattern, wherein the groove gradually expands the contact area as the tyre wears, which helps in maintaining the grip even in worn conditions. The circular wear indication in the middle of the tread diminishes over time, signalling that the tyre needs to be changed. To increase grip, the tyre also makes use of a broad contact patch and a high-carbon black compound. To improve stability and responsiveness at high speeds, the inside is constructed with a two-ply polyester framework and a twin steel belt. By avoiding wheel slide, these design elements contribute to steady performance even in high-torque electric vehicles.

Already a recipient of the prestigious Red Dot Design Awards (2022) and the ‘Green Tire’ seal from AutoBild (2023), the N’Blue 4Season 2 was also recognised in the same category for its eco-friendly design, which decreases tread wear, extends replacement cycles and lowers environmental impact. The tyre lasts longer and produces less waste thanks to a new compound that increases wear resistance by almost 30 percent over the previous model, supporting sustainability. Fine sipes are positioned in the middle of the tread blocks to guarantee uniform contact with the road. The outer tread's serrated edges enhance braking on snow, while the centre’s slanted support structure lessens block movement on uneven terrain for a more stable ride during the winter.

Travis Kang, Global CEO of Nexen Tire, said, “This award highlights our commitment to shaping a sustainable mobility environment through design-driven innovation. This accolade confirms our commitment to sustainability and quality. We will continue to strengthen our brand through innovation and responsible management.”

Bekaert has flagged off its first fleet of LNG-powered trucks in India in collaboration with GreenLine, the country’s leading provider of sustainable heavy trucking solutions. The joint initiative is aimed at supporting India’s vision for a gas-based economy and reducing the carbon footprint of road logistics.

The foundation of the collaboration with GreenLine is a mutual dedication to operational innovation and ESG standards. Bekaert has the infrastructure required to trial this effort in Chennai and Halol, with plans to expand following a six-month learning period, thanks to GreenLine's LNG ecosystem, which is supported by real-time telemetry and a smooth refuelling network. It is anticipated that each LNG truck will save up to 24 tonnes of CO₂ a year, making a significant contribution to Bekaert's targets of 65 percent of sales coming from sustainable sources and carbon net zero by 2050.

Dinesh Mukhedkar, Procurement Operations Lead – South Asia and Procurement Global Shared Service Centre Lead, said, “As part of our purpose, ‘Establishing the new possible’, and our ambition to lead in safe, smart and sustainable solutions, decarbonising logistics is an essential step. Heavy-duty transport contributes nearly 90 percent of emissions in Indian logistics. Switching to LNG helps reduce CO₂ by up to 30 percent and particulate matter by up to 91 percent compared to diesel. GreenLine’s mission and integrated support made them the ideal partner. Together, we are shaping a cleaner, more sustainable future for logistics in India.”