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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On 18 June, the prestigious 22nd ‘World Brand Conference and Release Ceremony of China's 500 Most Valuable Brands’ was held in Beijing, organised by the World Brand Lab. Demonstrating its industry leadership, Doublestar achieved an impressive brand valuation of CNY 116.208 billion (approximately USD 16.21 billion), securing the 93rd position overall and maintaining its position as the highest-ranked Chinese tyre brand for yet another year.

This recognition underscores Doublestar's strong market presence and consumer trust, built on decades of innovation and quality craftsmanship. Moving forward, the company has committed to strengthening its brand influence through continuous technological advancement and sustainable development. By focusing on research and production of safer, smarter and more environmentally friendly tyre solutions, Doublestar aims to not only meet evolving market demands but also drive the high-quality growth of China's tyre industry.

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Continental Tires has achieved a major sustainability milestone with all its European tyre production facilities now certified under the International Sustainability and Carbon Certification (ISCC) PLUS standard. The certification extends to plants in Lousado (Portugal), Puchov (Slovakia), Korbach (Germany), Sarreguemines (France), Otrokovice (Czech Republic) and Timișoara (Romania), along with the supporting Industria Textil do Ave textile plant in Portugal. The company's Hefei facility in China has also earned this recognition, expanding Continental's sustainable manufacturing network globally.

The ISCC PLUS certification verifies Continental's compliance with rigorous traceability and documentation requirements for renewable and recycled materials used in tyre production. This system enables the company to track sustainable inputs throughout the manufacturing process using the mass balance approach, which allows gradual incorporation of eco-friendly materials while maintaining existing production systems. Continental is currently increasing its use of certified materials, including bio-based synthetic rubbers and circular-process carbon black, as part of its strategy to include over 40 percent sustainable materials in tyres by 2030.

As a globally recognised standard established in 2010, ISCC certification promotes climate-friendly, deforestation-free supply chains across multiple industries. It covers sustainable biomass, recycled materials and renewable resources, providing a framework for transparent, responsible sourcing. For Continental, this achievement represents both a validation of current sustainability efforts and a foundation for future innovations in eco-conscious tyre manufacturing. The company's growing network of certified facilities demonstrates its commitment to reducing environmental impact while maintaining product quality and performance standards across its global operations.

Jorge Almeida, head of Sustainability for Continental Tires, said, “The ISCC PLUS certification of all our European tyre plants is an important milestone and a strong signal for a more sustainable industry in Europe. But we're not stopping there. Our plants in other regions will follow step by step, like our Hefei plant, which is already certified. We have a strong ambition to make our tyre production more sustainable worldwide across our entire supply chain.”

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Bandvulc has expanded its Wastemaster 5 tyre range with a new 315/70 size, enhancing options for urban waste collection and recycling vehicles. Originally launched in 2021, this robust tyre boasts a high load rating and is manufactured at ContiLifeCycle’s Ivybridge facility in Devon, which produces Bandvulc and ContiRe retread tyres.

The Wastemaster 5 incorporates ARMORBAND technology, featuring a reinforced rubber layer along the sidewall to resist scrubbing damage and prolong tyre life. Its advanced tread design includes wide zig-zag grooves for mud and water clearance, stone ejection features, stepped blocks and deep sipes for superior traction in tough conditions. This upgrade reinforces Bandvulc’s commitment to durability and performance in demanding waste management operations.

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Eurogrip Tyres, India’s top 2 & 3-wheeler tyre brand under TVS Srichakra Ltd, today launched two exclusive retail stores in Chennai – at Selaiyur and Villivakkam. These outlets will stock a full range of two-wheeler tyres, tubes and biking accessories like helmets, alongside offering tyre care, puncture repair, fitment services and engine oil changes.

Catering to scooters, commuter bikes, performance bikes and superbikes, the stores provide diverse tyre patterns and sizes. They will also handle warranty claims for customers. The Selaiyur store is located at J C Group, Plot no 3, Agaram Main Road, Chennai - 600 073, while the Villivakkam outlet is at ST Enterprises, Old no 39E/New no 103, MTH Road, Chennai - 600 049. These expansions reinforce Eurogrip’s commitment to premium service and accessibility.

T K Ravi, COO, Eurogrip Tyres, said, “We are happy to reach out to more customers through our new branded retail stores. In a city that has a bustling two-wheeler vehicle population, there is a need to have more outlets to expand our network. Chennai is an important market for us, and we had opened our first branded retail store in Velachery last May. The response from customers and riders has been encouraging and we are happy to be launching 2 more stores in the city – this will help bolster our brand strength here. We plan to have more such signature stores in different cities to make our products and services easily accessible to customers.”

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