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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The Association of Natural Rubber Producing Countries (ANRPC) recently welcomed Dr Satya Tripathi, Secretary General, Global Alliance for a Sustainable Planet (GASP), for a courtesy visit to its Secretariat. During this engagement, Dr Tripathi held discussions with ANRPC’s Secretary General, Dr Suttipong Angthong, as well as Secretariat members Dr Lekshmi Nair and Riska Pujiati. This initial dialogue marked the beginning of conversations aimed at fostering collaboration between ANRPC and GASP to advance sustainability within the natural rubber industry.

Both groups acknowledged systemic challenges facing rubber producing nations, including environmental harm, climate instability and economic volatility. They agreed the industry must embrace the global Green Transition, ensuring rubber enters markets through transparent, ethical, and sustainable supply chains.

The dialogue explored partnerships to strengthen sector resilience and ethical integrity, with special emphasis on supporting smallholders through transformative initiatives that deliver environmental and social impact. The meeting highlighted how high-impact collaboration drives climate adaptation, resilient ecosystems, sustainable livelihoods and inclusive prosperity. Dr Tripathi, a renowned development economist and former UN Assistant Secretary General, also participated in ANRPC’s COP30 side event promoting smallholder projects for net zero and beyond.

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Hankook Tire has announced a major brand advertising campaign set to run throughout the 2026 Major League Baseball (MLB) regular season, targeting fans across 26 stadiums in North America, including both United States and Canada. This initiative is designed to elevate the premium positioning of its globally unified ‘Hankook’ brand within the local market. The effort kicked off following the Opening Day game between the San Francisco Giants and the New York Yankees at Oracle Park in San Francisco on 25 March.

To broaden customer engagement, Hankook Tire will feature not only its core ‘Hankook’ brand identity but also its pioneering electric vehicle tyre lineup called ‘iON’, which is the world’s first full range of EV tyres, alongside the ‘Dynapro’ SUV tyre brand. A notable expansion this season is the inclusion of the Toronto Blue Jays’ home stadium in Ontario, Canada, allowing the company to extend its brand presence across the entire Canadian region for the first time.

Throughout the 2026 regular season, Hankook Tire plans to display its branding on major LED boards located in high-traffic areas such as behind home plate, along the first base line and on outfield fences. By integrating branding into these prominent ballpark locations, the company aims to naturally boost awareness of the ‘Hankook’ name among sports fans while strengthening its competitive edge in North America, a key global market for both SUVs and electric vehicles.

Since 2018, Hankook Tire has built on roughly five years of official MLB sponsorship to implement targeted sports marketing for local customers, reinforcing its premium image in the region. Following the successful World Baseball Classic, which showcased Major League talent, the company expects to enhance the innovative and dynamic image of its brand for both live spectators and baseball fans worldwide. Key markets featuring this high-visibility signage include New York, Boston, Atlanta and Toronto, among others, for the entire 2026 season.

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Magna Tyres has unveiled the M-TRUCK RG22, a commercial tyre aimed at the drive axle position of trucks engaged in regional haulage. This model is calibrated for shorter, repetitive routes where weather and road conditions change frequently. The tyre prioritises dependable grip and extended wear life, helping fleet operators achieve fewer replacements and more consistent handling.

The RG22 comes in sizes 295/60R22.5 and 315/60R22.5, with an 18 or 20 ply rating. Load and speed indices are 150/147K or 154/150L, and the tread carries both M+S and the three-peak mountain snowflake symbol. Fuel efficiency is rated C, wet braking grip is B, and noise output is 73 decibels, falling under the quietest A classification.

The RG22 effectively pushes water away from the contact patch, reducing aquaplaning risk on soaked regional roads. Its tread pattern promotes even wear, helping transport companies stretch mileage budgets. A sturdy internal construction withstands the stop-start stresses of regional work, offering a balanced solution where traction, longevity and all-weather reliability meet.

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TyreSafe, UK’s charity dedicated to raising tyre safety awareness, has launched Easter campaign to remind all road users that proper tyre maintenance is essential for a safe Easter getaway. With families carrying extra passengers, luggage and holiday treats, vehicles face increased strain, making tyre condition and pressure more critical than ever. Tyres are the only part of the car in contact with the road, so their health directly influences braking, handling and overall journey security.

Easter remains one of the busiest travel periods, and early signs point to another crowded weekend on British roads. According to the VisitEngland Domestic Trip Tracker 2025, a quarter of adults in Britain definitely planned an overnight Easter trip, with nearly one in five still undecided. As more families opt for UK breaks and rural staycations, the volume of traffic rises, and so does the reliance on tyres to cope with heavier loads and longer distances.

Carrying extra luggage, pushchairs, bikes and camping gear places significant additional weight on vehicles. Underinflated tyres under such loads lead to longer stopping distances, reduced stability, poorer steering control, greater risk of tyre failure and increased fuel consumption. Vehicle manufacturers provide specific pressure recommendations for fully loaded cars, yet many drivers overlook these adjustments before long journeys. Properly inflated tyres are vital to managing these risks.

Rural roads, popular for Easter escapes, remain the most dangerous in UK. A recent European Transport Safety Council report revealed that rural roads accounted for 59 percent of all UK road deaths in 2022, with over 10,100 fatalities in the past decade. While overall road deaths have fallen slightly, rural fatalities have not improved. Hazards such as sharp bends, narrow lanes, agricultural vehicles, poor lighting, potholes and slippery spring surfaces mean tyres must provide maximum grip and stability at all times.

TyreSafe’s own tread depth survey estimates that six million tyres on UK roads are illegal, meaning many vehicles are already unsafe before departure. To prevent Easter plans from unravelling, TyreSafe urges every driver to include tyre checks in their holiday routine, alongside packing and route planning, by embracing the simple ACT protocol: regular checks of air pressure, condition and tread depth.

Stuart Lovatt, Chair of TyreSafe, said, “Easter is a time for family, fresh air and making memories – but it’s also one of the busiest times on our roads. Heavily loaded vehicles, long journeys and rural routes can all increase risk if tyres aren’t properly maintained. Something as simple as adjusting your tyre pressures for a full car can make a significant difference to safety and performance. Before you hop off on your Easter adventure, take a few minutes to ACT – check your Air pressure, Condition and Tread. It’s a small step that could make a life-saving difference.”

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