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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Dr Suttipong Angthong, Secretary-General of the Association of Natural Rubber Producing Countries (ANRPC), was a distinguished speaker at the World Elastomer Technology and Engineering Forum (WETEF) in Shanghai from 13 to 16 September 2026. Co-organised with RubberTech China, the event attracted over 100,000 professional visitors, industry leaders, scholars and executives from dozens of countries.

His participation delivered strategic benefits for ANRPC and its members by raising natural rubber's profile amid global discussions dominated by synthetic elastomers and advanced materials. Aligning with WETEF's eco-friendly manufacturing focus, he promoted climate-positive practices, traceability and environmentally sound processing methods.

The forum also created direct dialogue channels with major consuming markets and international technical institutions, strengthening trade synergies. It provided valuable insights into breakthrough elastomer science, helping member nations adapt to shifting international market demands.

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Kuraray Co., Ltd. has contributed JPY 9,896,480, roughly USD 64,000, to four international nonprofit organisations. The funds were generated through employee participation in ‘100 Challenge’, a global initiative tied to the company’s centennial observances.

The World Food Programme received JPY 2,804,003, while UNICEF was granted JPY 2,474,120. WaterAid obtained JPY 2,405,394 and WWF was allocated JPY 2,212,963. Each organisation’s share corresponded directly to points accumulated by Kuraray Group staff.

The Group marked its 100th anniversary in June 2026, adopting ‘Possible starts here’ and a related brand story as the guiding concept for its centennial activities. While honouring those who built its first century, Kuraray is pursuing diverse efforts intended to shape the next 100 years, with employees worldwide at the centre. The company seeks to connect staff across departments, countries and languages, fostering unity and connection.

A dedicated app called ‘100 Challenge’, inspired by younger employees, formed one such effort. Participants completed 100 in-app tasks, earning points that supported social contribution activities. The app provided a shared experience regardless of location or role, with individual efforts contributing to both a commemorative mosaic artwork and charitable donations. By combining small individual challenges, the initiative illustrated how personal actions can generate meaningful collective impact, reflecting long-held Kuraray Group values.

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TyreSafe has entered a new partnership with Staffordshire Police, reinforcing a joint commitment to improve road safety and reduce fatalities and serious injuries across the county. The collaboration aims to highlight the critical role tyres play in protecting road users by encouraging simple, regular checks of pressure, tread depth and overall condition.

The value of this preventative approach was recently demonstrated during a multi-agency enforcement operation at the DVSA Vehicle Inspection Site in Doxey. Held on 25 August, Operation Doxey involved Staffordshire Police, West Mercia Police, DVSA, Datatag, the Forensic Collision Investigation Unit and TyreSafe. Inspectors directed 30 vehicles into the site, covering leisure vehicles, towing vehicles, light commercial vehicles and goods vehicles.

Seven tyre and wheel-related defects, mechanical risks and pressure discrepancies were identified. These included a tyre cut through to the cord, which received an immediate prohibition notice, a tyre running roughly 30 percent below recommended pressure, an overweight light commercial vehicle with a nail embedded in a tyre and all four tyres underinflated, a significant rear axle pressure imbalance, a missing wheel nut and an 11-year-old tyre. Leisure vehicle owners generally showed good tread awareness, though pressure maintenance remained an issue, while commercial vehicles presented several preventable defects.

Staffordshire has one of UK’s statistically safest road networks, yet serious collisions remain a concern, particularly on single carriageways. Rural bends, changing speed limits and limited visibility add risk, while motorcyclists and vulnerable road users are disproportionately affected. Common factors include failing to look properly, misjudging speed or path and driving too fast or carelessly. TyreSafe now works with over 260 organisations, and this partnership encourages Staffordshire motorists to make tyre checks routine.

Stuart Lovatt, Chairman, TyreSafe, said, “We are delighted to welcome Staffordshire Police as a TyreSafe partner. While Staffordshire has a strong road safety record, every serious collision has potentially devastating consequences for those involved, their families and their communities. The recent Operation Doxey enforcement activity demonstrates exactly why preventative vehicle maintenance matters. Across just 30 vehicles, inspectors identified a number of serious tyre and wheel defects, including a tyre cut to the cord, significantly incorrect tyre pressures, an embedded nail, a missing wheel nut and a tyre that was 11 years old.

“These findings are a powerful reminder that problems are not always obvious from behind the wheel. Simple checks before a journey can help identify issues before they become a danger on the road. Different roads present different challenges, particularly rural and single carriageway roads where the consequences of losing control or being unable to stop safely can be especially severe. Road safety requires a collective effort, and partnerships such as this are incredibly important. By combining the reach and expertise of Staffordshire Police with TyreSafe’s specialist knowledge and campaigns, we can help more road users understand the simple but crucial role their tyres play in keeping themselves and others safe.”

Police Sergeant Adam Van de Sande, Staffordshire Road Crime – Proactive & Harm Reduction Team, said, “Keeping people safe on Staffordshire’s roads requires everyone to play their part. We are committed to working with partners to reduce the number of people killed and seriously injured on our road network. Operation Doxey demonstrated the value of partnership working, with officers, vehicle examiners and road safety specialists able to identify a range of defects and safety issues before those vehicles continued their journeys.

“Vehicle safety is an important part of that responsibility, and tyres are fundamental to a vehicle’s ability to stop, steer and maintain grip. We are pleased to be working with TyreSafe to raise awareness and encourage motorists to make regular tyre checks part of their routine vehicle maintenance. Our message to road users is simple: don’t wait for something to go wrong. Take a few minutes to check your vehicle and make sure it is ready for the road.”

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The AZuR Network has been honoured with the German Award for Sustainability Projects 2026 in the C2C/Recycling category for its ‘Retreading: Climate Protection on Wheels’ project. The recognition highlights the network's efforts to expand tyre retreading across Germany and Europe, thereby extending the useful life of tyres. Retreading works by reusing a suitable used tyre casing and applying a fresh tread, keeping a substantial share of the original tyre in circulation.

A life cycle assessment commissioned by AZuR and carried out by the Fraunhofer Institute UMSICHT compared retreaded tyres with equivalent new ones. Under the conditions examined, producing a retreaded truck tyre generated roughly 135 kilogrammes less greenhouse gas emissions, a reduction exceeding 60 percent. The process also reuses considerable portions of the existing tyre casing, reinforcing its environmental advantages.

The jury underscored the project's scalability and its relevance to the industry. Official documentation further noted the political integration of the topic as a key strength, with the EU taxonomy confirmation in 2025 representing a tangible milestone. The award places AZuR among well-known companies and innovative projects, including a climate protection cooker initiative in Cameroon, a capsule-free coffee system and a mental health awareness campaign.

Knauf secured first place in the same category with its circular gypsum supply chain, while Schmitz Cargobull led the Mobility and Logistics Solutions category. Other first-place winners included DEKRA, Hansgrohe, Pfleiderer Germany and SBRS. Presented by DISQ with ntv and DUP UNTERNEHMER under Brigitte Zypries' patronage, the 2026 edition saw 433 nominations, with 46 organisations recognised across 19 categories on 17 September in Berlin.

Christina Guth, Network Coordinator, AZuR, said, “This award belongs to our entire network. Retreading only works when many stakeholders collaborate along the value chain – from certified end-of-life tyre recyclers, tyre manufacturers and retreaders to retailers and fleet operators, all the way to academia. The award highlights the potential of using high-quality tyres for longer and keeping their casings in circulation.”

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