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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Toyo Tire Corporation said Mitsubishi Corporation has ceased to be a major shareholder after tendering its entire holding through a treasury share buyback, ending its status as the company’s largest shareholder.

The change took effect on 10^th August , 2026, following Toyo Tire’s acquisition of its own shares through off-auction trading (ToSTNeT-3). Mitsubishi tendered all its shares, excluding less than one unit, as part of the transaction.

As a result, Mitsubishi is no longer classified as a major shareholder or associated company of Toyo Tire, the company said.

Before the transaction, Mitsubishi held 30,822,206 shares, equivalent to 20.07 percent of total voting rights, and ranked as the largest shareholder. Following the change, its holding has effectively been reduced to zero.

The move follows Toyo Tire’s earlier announcement on August 7, 2026 regarding the termination of its capital and business alliance with Mitsubishi, alongside plans to repurchase its own shares.

Toyo Tire said the change would have no impact on its consolidated financial results.

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Linglong Tire has become the first Chinese tyre manufacturer to join the Global Data Service Organization (GDSO) as a full member, marking a step in the industry’s efforts to standardise and exchange tyre-related data globally.

The company joins the non-profit body as its fourteenth member. GDSO was established in January 2022 by Bridgestone, Continental, Goodyear, Michelin and Pirelli to facilitate the digital exchange of tyre data and develop common standards across the sector.

Moh Wahi, Head Of Truck And Bus Tyre Development at Linglong Europe, said: "By joining the GDSO as a Full Member and providing reliable data, we want to be the first Chinese tyre manufacturer to make a positive contribution to the further development of the tire industry and set new standards for the efficient processing of tire data in the digital age."

Riccardo Giovannotti, Secretary General of GDSO, said: "With Linglong Tire as a Full Member, GDSO is gaining one of the leading Chinese tire companies which is committed to digitalization and sustainability in the industry. Together, we will further make progress in developing standards for data processing and future-oriented solutions."

Shandong Linglong Tire Co., Ltd., founded in 1975, operates seven research and development centres globally and employs almost 20,000 people. The company runs nearly 200,000 sales outlets and exports products to 175 countries.

It supplies tyres to more than 200 production bases for over 60 automakers and has manufacturing facilities across China, Thailand and Serbia, with plans to expand further overseas.

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TyreSafe, UK’s charity dedicated to raising tyre safety awareness, has joined forces with Sussex Police’s Road Safety Team to introduce a pioneering digital reference tool for frontline officers. The initiative equips police with immediate, device-accessible tyre safety data during roadside stops.

Developed as a local pilot, the application enables consistent vehicle examinations and improves driver communication regarding tyre dangers. It offers specific checklists for diverse vehicle categories, including motorcycles, cars, heavy goods vehicles, light commercial vans and towed trailers. The system further incorporates guidance on part-worn tyres, common queries and educational talking points.

Following its Sussex trial, the programme holds potential for nationwide adoption across UK police forces. This deployment underscores Sussex Police’s dedication to roadway innovation and reinforces the essential contribution of proper tyre maintenance to overall public safety.

Stuart Lovatt, TyreSafe Chair, said, “This partnership with Sussex Police is a landmark moment for tyre safety enforcement and education. By putting reliable, accessible tyre safety guidance directly into the hands of frontline officers, we can ensure safer vehicles on our roads and help prevent avoidable collisions and breakdowns. Sussex is leading the way, and we hope this model will soon be adopted nationally.”

Superintendent Jo Grantham, Head of Roads Policing, Sussex Police, said, “Our officers are committed to keeping road users safe, and having instant access to this tyre safety resource makes a real difference on the ground. It supports enforcement while also giving us the tools to educate drivers more effectively. We’re proud to be working with TyreSafe on this project and to be the first police force in the country to pilot it.”

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The UK Towing Safety Alliance (UKTSA) has published a comprehensive four-year analysis of incident data from National Highways’ Strategic Road Network, covering 2022 to 2025. The findings reveal a 23 percent rise in total towing-related incidents, driven primarily by a maintenance crisis affecting utility and commercial trailers. While traffic collisions involving towed vehicles decreased by 17 percent, mechanical breakdowns now constitute 77 percent of all towing-related incidents, highlighting vehicle and trailer condition as the sector's foremost challenge.

The data coincides with SMMT Motorparc 2025 figures showing Britain's vehicle fleet at its oldest recorded level, with average car age reaching 9.7 years. The summer harvest season has also arrived, bringing agricultural trailers back to roads after months of disuse. NFU Mutual research indicates collisions involving agricultural vehicles are 56 percent more likely between May and September, reinforcing the need for pre-journey roadworthiness checks.

Utility and agricultural trailers now account for nearly half of all towing-related callouts, surpassing 3,000 incidents in 2025. Regionally, the North West has overtaken the South East as the most incident-prone area, with trailer failures surging 60 percent since 2022, while the North East recorded a 55 percent increase. A growing divide exists between leisure and commercial towing sectors.

Leisure sector improvements, including fewer horsebox incidents and regional caravan reductions, suggest awareness campaigns are yielding positive results. However, utility trailer failures continue climbing, indicating maintenance standards across commercial and domestic sectors require greater attention. Regular servicing, correct loading and proper coupling remain essential to prevent avoidable incidents.

For working trailers, summer represents peak operational period, with agricultural and utility trailers seeing intensive use while rural roads become busier with tourists and cyclists. The Alliance emphasises that trailers stored for extended periods require thorough inspections before returning to service.

The UKTSA urges all towers to perform three essential checks covering tyres, load and connection before every journey. Tyres must be inspected for pressure, tread and deterioration; loads correctly distributed and couplings and electrical connections verified. The Alliance will place ‘The Working Trailer’ at the centre of safety campaigns, collaborating with industry partners to boost maintenance awareness and reduce preventable breakdowns across the Strategic Road Network.

A spokesperson for the UK Towing Safety Alliance said, “It’s encouraging to see fewer collisions involving towing vehicles, which suggests that drivers are becoming more aware of safe towing practices. However, that progress is being undermined by a growing number of preventable mechanical failures. The challenge is no longer simply about how people tow – it’s increasingly about what they’re towing and the condition it’s in. As both tow vehicles and trailers get older, regular maintenance has never been more important.”

Stuart Lovatt, Chair of TyreSafe, said, “Harvest season places extra demands on both vehicles and trailers, particularly those that may only be used for a few months each year. One of the most common issues we see is tyres that appear to have plenty of tread but have deteriorated through age, weathering or prolonged storage. Whether you’re towing a livestock trailer, plant trailer, horsebox or caravan, tyres should always be inspected for correct pressure, damage, cracking and signs of ageing before every journey. A few minutes spent carrying out these checks can prevent breakdowns and significantly improve safety for everyone using our roads.”

Sarah Smithurst MBE, COO, National Trailer & Towing Association (NTTA), said, “Across the NTTA network, we’re seeing a noticeable increase in enquiries from people looking to refurbish older trailers or source second-hand trailers, including imported models, as a more affordable alternative to buying new. While extending the life of a trailer is often entirely appropriate, it’s essential that owners understand that trailers are not maintenance-free. Many have been in service for years, sometimes decades, and components naturally deteriorate over time, even if the trailer has seen relatively little use. Every trailer should be thoroughly inspected before it returns to the road, with particular attention paid to tyres, brakes, bearings, couplings and lighting. Investing in regular servicing and maintenance is far less costly than experiencing a breakdown – or worse, being involved in an incident. The NTTA continues to help and advice new and old trailer users about safety and many are asking for help when towing, especially the reversing aspect of a trailer, now the B&E test was withdrawn. We are also seeing more trailers being repatriated from North America and Europe rather than purchasing new in the UK.”

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