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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Hankook Tire concluded Round 2 of the 2026 FIA World Rally Championship, Rally Sweden, on 15 February in the Umeå region, where its Winter i*Pike SR10W tyre was put to the ultimate test. As the championship’s sole rally tyre supplier, Hankook equipped all competing crews with this dedicated winter tyre, which features specially engineered ice-rally stud pins. Designed to conquer the most severe icy environments, its asymmetric tread pattern works in tandem with the studs to provide exceptional grip, powerful braking and unwavering high-speed stability on frozen surfaces.

Rally Sweden, first held in 1950, is unique on the calendar as the only event contested entirely on snow and ice. Crews were challenged by 18 special stages covering around 300 kilometres, with competition intensified by speeds reaching up to 200 kmph and rapid temperature fluctuations. These punishing conditions demanded precise car control, reliable tyre traction and steadfast braking performance, making the choice of the Winter i*Pike SR10W critical for success.

Following a fierce contest, Toyota GAZOO Racing’s Elfyn Evans and co-driver Scott Martin claimed victory by a margin of 14.3 seconds, securing their second consecutive win in Sweden. Having also finished second in the season opener at Rallye Monte-Carlo, this result propelled the pairing to the top of the championship standings with 60 points.

The WRC now turns its attention to the formidable Safari Rally Kenya, scheduled for 12 to 15 March 2026 near Naivasha. This event is renowned as one of the most gruelling on the circuit, where crews must navigate extreme heat, mud from heavy rainfall and rapidly changing weather.

Hankook’s commitment to the sport extends beyond event supply. The company continues to refine its high-performance rally technology through intensive collaboration with the FIA and major automotive manufacturers, having completed over 2,000 kilometres of real-vehicle testing across eight countries. With its exclusive tyre supply agreement for all WRC classes covering the 2025 to 2027 seasons, Hankook is reinforcing its premium brand identity and solidifying its leadership in motorsport engineering.

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Ecolomondo Corporation, a leading Canadian innovator in sustainable scrap tyre recycling technology, has appointed Craft Capital Management, LLC as its strategic investment banking advisor. This partnership is designed to bolster Ecolomondo’s capital markets strategy, with a focus on financing initiatives and a planned uplisting to the NASDAQ. Securing this position is a key step for the company to obtain the necessary capital for its global expansion.

Eliot Sorella, Ecolomondo’s Executive Chairman, highlighted that Craft Capital’s successful history of providing capital solutions is well-aligned with the company's goal to scale up as a major supplier of recovered carbon black and tyre pyrolysis oil. These materials are produced using Ecolomondo’s proprietary Thermal Decomposition Process. As worldwide demand for circular and sustainable materials grows, this advisory engagement is seen as a vital move to advance the company's market position and support its next growth phase.

Craft Capital, a full-service brokerage firm with over a century of combined financial experience, offers customised investment banking services and connects clients to a broad network of family offices and institutional investors.

Sorella said, “Craft Capital’s proven track record in delivering capital solutions aligns strongly with our strategy to scale as a leading producer of recovered carbon black (rCB) and tyre pyrolysis oil (TPO) using Ecolomondo’s proprietary Thermal Decomposition Process (TDP). As global industries accelerate their transition towards circular and sustainable materials, this engagement is an important step in advancing our capital markets strategy and supporting our next phase of growth.”

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Continental is set to make a significant impact at the upcoming Tire Technology Expo in Hannover with a strong presence at the technical conference scheduled for 3 March 2026. The company will kick off the event with a major presentation centred on the evolution of tyre technologies designed to meet the demands of autonomous driving. Dr Andreas Topp, who leads Platform Development and Industrialisation for passenger car tyres at Continental, will illustrate how the vision of autonomous vehicles is transitioning into everyday reality and how the tyre manufacturer is proactively developing innovative solutions to support this shift.

In addition to the opening session, Continental experts will deliver three further presentations, each addressing critical areas of tyre science and environmental regulation. One of these will explore the use of recovered carbon black derived from end-of-life tyres as a filler material. Professor Jorge Lacayo-Pineda, a specialist in materials evaluation, will delve into the complexities of identifying this material within vulcanised rubber compounds. Recovered carbon black, primarily obtained through pyrolysis, represents a milestone as the first industrially scalable filler sourced from discarded tyres. It is not considered a direct substitute for conventional carbon black but rather a distinct category of filler due to its unique composition, which includes carbon residues and a specific thermal background. Professor Lacayo-Pineda will examine the technological and regulatory possibilities that arise from detecting this material in new tyre compounds, focusing on reliable identification techniques such as electron microscopy and molecular spectroscopy.

Another key presentation will broaden the conversation around tyre emissions. Dr Frank Schmerwitz, a senior test engineer specialising in tyre wear, will address the limitations of current discussions that predominantly focus on tyre and road wear particles. He will highlight additional pathways of mass loss that are not captured by conventional measurements. His talk will consider the release of nanoparticles, the persistence of wear residue on road surfaces and the chemical degradation of this material due to environmental factors like oxygen and ultraviolet light, aiming for a more complete scientific picture.

The final presentation will tackle the complexities of modern tyre development in the context of new regulatory frameworks. Dr Pavel Ignatyev, an expert in rubber friction and wear physics, will discuss how the introduction of standardised abrasion limits and measurement methods under the Euro 7 regulation is reshaping innovation in the industry. He will explain the various parameters influencing tyre wear and how they interact with these new requirements. Through simplified models, he intends to demonstrate the intricate nature of tyre wear and outline the collective challenges that remain for the industry, emphasising that a deep understanding of these dynamics is crucial for translating regulatory mandates into effective technological advancements.

Dr Topp said, “The future of self-driving vehicles has begun. We are developing tyre technologies and products that meet the unique technical requirements of these vehicles. This includes topics such as interaction with smart vehicle dynamic controls, optimised fleet operations and tailored solutions for specific use profiles.”

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The concluding day of 2026 F1 Pre-Season Testing at the Bahrain International Circuit saw Charles Leclerc set the overall fastest lap of the entire six-day programme. The Ferrari driver delivered a time of 1:31.992s on the C4 compound Pirelli tyres during the final hour of running, improving by eight-tenths of a second on the previous benchmark established by Kimi Antonelli. This performance placed him ahead of Lando Norris in the McLaren, who recorded a 1:32.871s on the C3 tyre. Max Verstappen and George Russell followed, with times of 1:33.109s and 1:33.197s, respectively, both also set on the C3 compound. Notably, none surpassed Leclerc's own leading time on that particular compound, a 1:32.655s. Pierre Gasly rounded out the top times, utilising the softest C5 tyres to post a 1:33.421s.

The C5 compound saw limited use on the final day, employed only by Alpine and Williams for short-run simulations. Aston Martin, despite having the tyre available, opted not to run it and instead completed just six laps on C3s before their session was curtailed. In contrast, teams focused on different aspects of performance. Gabriel Bortoleto and Arvin Lindblad set the pace on the harder C1 and C2 compounds, respectively. The day was also notable for the absence of several drivers, including Fernando Alonso, Lewis Hamilton and Alex Albon, who did not participate in any track action.

Beyond outright speed, teams dedicated significant effort to long-distance evaluation. Gabriel Bortoleto completed 25 laps on the C2 compound for Audi, while Esteban Ocon undertook 24 laps on C1s for Haas. Ocon was also the sole driver to run intermediate tyres, completing four laps to assess front wing behaviour. Over the entire six-day test, a total of 41,366 kilometres were covered across all 11 teams, a distance exceeding the Earth's circumference. The C3 compound proved the most popular, accounting for 61 percent of all laps. In total, 591 sets of slick tyres were utilised throughout the pre-season, with 326 of those deployed in the final three days alone.

Mario Isola, Pirelli’s Motorsport Director, said, “The radical changes introduced to the cars have inevitably shifted the teams’ focus towards power units and aerodynamics rather than tyres over the last few days. The final stages of testing are usually dedicated to optimising the car-tyre package, but it is clear some teams haven’t reached that point yet. Generally speaking, track feedback has been consistent with our simulation expectations. Drivers were able to gain confidence with the entire Pirelli range through both performance trials and long runs, even using the C4 and C5 compounds which aren’t particularly suited to a circuit like Sakhir.

“Mechanical resistance appeared strong across all options, with no signs of graining or blistering. Degradation levels are almost certainly higher now than what we expect for the Bahrain race, when temperatures will be lower and cars more developed. A central theme this season will certainly be balancing temperatures between the axles, especially ahead of the first race in Melbourne. The lower loads of a street circuit might require more intensive tyre preparation or differentiated tyre blanket temperatures, particularly in qualifying. In any case, it will be interesting to discover in Australia how much teams have been ‘sandbagging’ their engine power to avoid showing their hand. We only have to wait a couple of weeks to see the true pecking order.”

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