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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In a landmark event for the United Kingdom's agricultural sector, Trelleborg Tires successfully hosted the inaugural UK edition of its Tractor Driver of the Year competition. The prestigious grounds of Prestwold Hall in Leicestershire provided the setting on 16 October 2025 for a gathering of the nation's most skilled operators. These drivers were put through a rigorous practical examination of their abilities, facing a circuit of demanding stations that evaluated their agility, pinpoint accuracy and overall vehicle command.

The contest, which ran throughout the day, required competitors to master a suite of complex manoeuvres. Each task was engineered to push the limits of their expertise using a fleet of Valtra tractors equipped specifically with Trelleborg’s TM1000 ProgressiveTraction and TM1060 tyres. After an intense series of trials, Mitchell Oldershaw emerged victorious, securing the coveted title of Tractor Driver of the Year UK 2025. His winning run, a remarkable feat of precision and speed completed in just eight minutes and forty-nine seconds, earned him the grand prize of an Everyman Racing Platinum Package. The successful execution of the event was supported by technical collaborations with Valtra and Chandlers FE Ltd, which supplied the necessary machinery and trailers.

This UK debut represents a significant international expansion for the competition, which has long been a cornerstone event for farming professionals in Italy. Trelleborg Tires has demonstrated a clear commitment to fostering a hands-on community for the agricultural sector, creating dynamic platforms where operators can directly engage with advanced tyre technology. By translating technical innovation into tangible on-ground performance, the company continues to underscore the critical relationship between superior tyre engineering and enhanced productivity in modern farming. The event’s success paves the way for future gatherings that celebrate skill, technology and community spirit.

Celebrating his victory, Oldershaw said, “A big thank you to everyone for organising such a great event. It’s been a fantastic day – I came for the fun and didn’t expect to win! I’m already looking forward to coming back next year to defend the title!”

Hawra Hussain, Marketing Manager UK & ROI at Yokohama TWS, said, “Tractor Driver of the Year is all about putting farmers’ skills to the test and showcasing real performance in the field. Every detail of this event – from the venue to each challenge – was designed to create an authentic and rewarding experience. Connecting directly with farmers helps us understand their real-world needs and lets them see our tyres in action, demonstrating the superior traction and durability that drive high productivity every day.”

Seth Bradford, Sales Support Manager for UK & Ireland at Valtra, said, “This event has been a great opportunity to meet the agricultural community and strengthen our collaboration with Trelleborg Tires. We work together, as we offer extensive range of Trelleborg VF tyres that work seamlessly with our factory-fitted central tyre inflation system. This integrated approach enhances customisation and maximises performance and comfort in the field.”

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The EU Commission’s proposal to amend the EU Deforestation Regulation (EUDR) has been met with sharp criticism from the German rubber industry. While supportive of the goal to reduce bureaucracy, the industry argues that the amendment, presented on 21 October 2025, fundamentally misses the mark. According to Boris Engelhardt, Managing Director of the German Rubber Industry Association (wdk), the changes create new, significant problems rather than solving existing ones. The association is therefore reiterating the introduction of ‘first-touch principle’ to achieve the regulation's goals without crippling businesses.

The core of the issue lies in a new requirement for handling supply chain data. Instead of each company registering its products, the proposal mandates that a single reference number from the first importer must be passed through the entire supply chain. Engelhardt warns that this places an immense technical and administrative burden on companies. Their IT systems, built at great cost for the original EUDR rules, cannot process and forward countless supplier numbers, requiring expensive, time-consuming upgrades that cannot be completed by the 2025/2026 deadline.

Beyond the technical impracticality, the industry identifies a more severe flaw: the compulsory sharing of these reference numbers would force companies to disclose their confidential supplier relationships to all downstream competitors. This is viewed as an unacceptable violation of trade secrets.

As a solution, wdk champions the ‘first-touch principle’. This approach would concentrate all regulatory oversight exclusively on the first economic actor who brings a covered raw material into the EU. All subsequent companies within the EU's single market would be exempt from the EUDR's burdens. The wdk contends that this system would fully meet the deforestation regulation's environmental objectives while instantly resolving the IT system overload and robustly protecting sensitive commercial information for all businesses in the value chain.

Engelhardt concluded, "After two years of tinkering, fixing laws at the last minute with a hasty needle doesn't work. That's not how democratic legislators work. The proposed amendment to the EUDR creates ambiguities and gaps, particularly regarding corporate liability, the consequences of which are unforeseeable. The only solution can be: EUDR with a first-touch principle!”

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The Nokian Tyres Green Step Ligna concept tyre, a collaborative effort with UPM, secured top honours at the 2025 New Wood competition. This prestigious award recognises groundbreaking wood-based bioeconomy solutions that tackle global challenges and advance the Sustainable Development Goals. The jury assessed entries on their societal importance, market potential and innovative use of wood, ultimately selecting a winner seen as a benchmark for the industry.

The concept tyre earned praise for making a concrete advance towards sustainable transport and materials production. It serves as a powerful example of how ecological considerations can be integrated with high performance, offering a blueprint for other companies. Its core innovation involves a significant material substitution in the tyre's sidewall, where conventional fossil-based fillers have been replaced with UPM BioMotion, a renewable filler derived from lignin.

As fillers determine much of a tyre's durability and performance and account for roughly a third of its mass, this shift is particularly impactful. Lignin is a natural compound abundant in wood and is generated as a by-product of pulp manufacturing. The successful application of this bio-based material in a demanding component like a tyre sidewall signals a pivotal shift for the entire industry, marking a substantial leap in the journey toward a future built on renewable resources.

Pauli Aalto-Setälä, a jury member of the New Wood 2025 competition, said, “Sometimes the most powerful innovations don’t alter the product itself, but the materials behind it – transforming it into something truly sustainable.”

Martta Fredrikson, Chair of the New Wood competition jury, said, "This year, the utilisation of industrial side streams was particularly highlighted in the New Wood competition. The lignin-based tyre material that won the competition and the second-placed wood fibre insulation are excellent examples of this.”

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Bridgestone has earned significant acclaim from the German automotive publication Auto Bild, being jointly awarded the 2025 winter tyre 'Manufacturer of the Year' title. This prestigious honour was largely driven by the outstanding performance of the company's premium winter tyre, the Blizzak 6, in the publication's rigorous annual evaluations.

The manufacturer’s success extended beyond winter tyres, with the Bridgestone Turanza All Season 6 also achieving a top podium finish. It secured second place in the all-season category for 'Manufacturer of the Year' and was declared a joint test winner in Auto Bild’s specific SUV All-Season 2025 Tyre Test. The tyre earned an exemplary overall rating after proving to be a strong and balanced all-rounder across a wide range of performance criteria.

Further validating these results, independent testing by TÜV SÜD confirmed the Turanza All Season 6's best-in-class wet braking capabilities, alongside excellent braking in both dry and snowy conditions. The tests also highlighted its exceptional snow traction, cornering and handling. An additional benefit is a 20 percent improvement in mileage over its predecessor, contributing to greater cost efficiency and a reduced environmental footprint.

Similarly, the winter-focused Blizzak 6, launched in 2024 as the successor to a multiple-award-winning model, has demonstrated top-tier performance in TÜV SÜD assessments. It is a top-rated tyre for snow braking and traction and is reported to offer the shortest stopping distances on wet roads. It also boasts a substantial 32 percent improvement in mileage.

A key technological foundation for both of these award-winning tyres is Bridgestone's ENLITEN Technology. This next-generation engineering approach is designed to deliver customised and uncompromised performance while simultaneously advancing sustainability and enhancing electric vehicle readiness across the company's product portfolio.

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