The future of tyres in the driverless age

1886 is often regarded as the birth year of the modern car. This was the year that Karl Benz filed a patent for a “vehicle with a gas engine” to the Imperial Patent Office in Berlin.

As you’d expect from a vehicle designed approximately 130 years ago, the “Benz Patent Motor Car” bears little resemblance to modern day cars. Indeed the open-top, two-seater cab and thin tricycle wheels, coupled with an output of barely one horsepower is a far cry from the impressive machines that hurtle along our motorways today.

That being said, they do have one feature in common – the requirement for a human driver. Yet even this final vestige of resemblance seems likely to be relegated to the past with the rise of autonomous vehicles (AVs).

Undoubtedly, the arrival of AVs and novel ways of deploying AVs, will revolutionise the landscape of the automotive industry, transforming the requirements of cars of the future. Tyres in particular are set for an AV revolution.

Tyres in modern day vehicles, quite literally, bear a huge burden. They are responsible for carrying the weight of the vehicle, adapting to ever changing road conditions, and maintaining direct contact with the road to ensure passenger safety.

Now, with the rise of AVs, tyres will have to fulfil these responsibilities in the absence of any driver input. Accordingly, tyre innovation will be vital to keeping pace with such a revolutionary change to the automotive industry.

Tunnel vision

It is anticipated that AVs in the future will form large commercial fleets of vehicles that can be hailed on command to whisk a passenger from A to B. And, with the pioneering advances made by companies such as Waymo, Cruise and Tesla, this vision may soon become a reality.

For example, Elon Musk’s tunnel transportation venture The Boring Company (a pun that, one can assume, is absolutely intended) has nearly completed its Loop tunnel system under Las Vegas, which is intended to provide a “high-speed underground public transportation system in which passengers are transported via compatible autonomous electric vehicles (AEVs) at up to 155 miles per hour”.

And The Boring Company already has plans underway to extend their subterranean tunnel systems to other cities to “solve the problem of soul-destroying traffic”.

Clearly, fleets of AVs shuttling multiple passengers back and forth across cities will rarely stand idle. This is in stark contrast to the average household car which spends only about 4% of its time on the move; the remaining 96% of the time being spent parked at home or elsewhere.

It follows that tyres – being the touch points between road and vehicle – will bear the brunt of this increase in drive time, reinforcing their position as a crucial new area for development.

And so, faced with this AV future, the seemingly humble tyre has stepped into the spotlight. With tyre manufacturers investing heavily in tyre innovation to get ahead of the curve and meet the new requirements imposed by AVs.

Concept tyres (i.e. tyres that showcase the latest innovations) unveiled by the major players provide a glimpse of what could lie ahead, illustrating some of the radical innovations that may truly reinvent the wheel.

Easy rider

Conventionally, a driver “feels the road” through the steering wheel. That is, vibrations from the tyres run up the steering wheel to provide the driver with information on the road conditions – this is known as “haptic feedback”. This acts as a sensory cue to assist the driver’s response to any changes that may occur at the tyre-road interface.

Of course, doing away with the driver in AVs means that “feeling the road” becomes less important. Instead, smoothness of the ride and rider comfort will take priority. Especially because AVs will likely be treated as a refuge for riders to catch-up on business or leisure time.

Goodyear’s futuristic Eagle-360 (also demonstrated in this video) is an AV concept tyre that has rider comfort placed as a priority. Its spherical design represents a radical change from tyres of today. Being spherical the Eagle-360 possesses an infinite number of axes of rotation to provide ultimate manoeuvrability, which is said by Goodyear to provide “a smooth ride by creating a fluid, lateral movement”.

And, to further ensure ultimate manoeuvrability, the spherical tyres are “held” to the body of the car by magnetic fields, similar to those used in magnetic levitation trains. The lack of any direct connection between the tyres and the car body also acting to reduce noise and increase rider comfort.

It’s clear to see that the Eagle-360 is a complex piece of kit and won’t be going into mass production anytime soon. Indeed, Goodyear emphasise that the Eagle-360 is “purely a concept tyre”. But, in any event, it does make for a compelling showpiece of what the future could bring.

Another example of an AV concept tyre designed for rider comfort is Hankook’s Hexonic (also demonstrated in this video), which was recently displayed at the Essen Motor Show in 2018.

The Hexonic tyre features a dynamic tread that actively changes with the road conditions (assisted by seven sensors that scan and analyse the road in real time).

The tread of the Hexonic is divided up into a series of hexagonal scales that can move apart to create water channels to improve water drainage. And the middle of each hexagonal scale also contains a “Y”-shape that can project or retract from the surface to adjust the level of grip and enhance cornering performance.

The overarching concept behind the Hexonic being that the dynamic tread can adapt and respond to the road conditions automatically and in real-time to maximise rider comfort.

In the context of commercial fleets of AVs, attracting a large customer base by ensuring rider comfort is one thing. But, as with any business model, to be sustainable it also needs to be profitable.

The price of inflation

Pneumatic tyres (i.e. air-filled tyres) have long dominated the tyre industry since their conception around 175 years ago (as explored in our blog "Patents driving tyre innovation"). To the extent of completely overshadowing their non-pneumatic (i.e. airless) companions.

This isn’t surprising considering that pneumatic tyres outperform non-pneumatic tyres in nearly every respect.

However, when it comes to eliminating the risk of blowouts or flats, airless tyres are triumphant.

Accordingly, airless tyres present an attractive option for commercial fleets of AVs, where time spent in the garage (e.g. to maintain tyre pressures or fix a flat) equals money down the drain. And, of course, eliminating the possibility of a blowout or flat is advantageous for rider safety.

And so, with the advent of fleets of AVs, a flat-proof tyre that can equal or best the performance of its air-filled companions could prove to be an extremely lucrative asset. Therefore, it’s of little wonder that the major players have turned their attention to airless tyre technology in the context of autonomous vehicles.

For instance, Bridgestone and Sumitomo Rubber/Falken have each unveiled concept stage airless tyres. Both of which appear to utilise a flexible spoke structure to support the weight of the vehicle.

And Michelin in collaboration with General Motors have taken this a step further with the UPTIS (Unique Puncture-Proof Tire System) – also demonstrated in this video. The UPTIS features an aluminium wheel assembly surrounded by flexible spokes made of composite rubber and proprietary high-strength resin embedded fiberglass.

Prototype testing of the UPTIS with Chevrolet Bolt Electric Vehicles commenced in 2019. And mass production is expected to start as early as 2024, with Steven Kiefer (General Motors’ senior vice president of global purchasing and supply chain) pointing out to Autocar that the “[UPTIS] may fit exceptionally well into the fleet autonomous vehicles that we’re conceptualising right now”.

Driving change

The concepts described above represent just a tiny fraction of the innovations prompted by the rise of AVs. For instance, another key area of tyre development includes that of “smart tyres” (explored in our blog "Smart tyres: under pressure to get smarter"), i.e. tyres that can be connected to and support a fully autonomous system.

Tyre durability and longevity will also grow more important if fleets of AVs are to achieve near continuous operation. As such, it’s anticipated that tyre manufacturers will seek to prioritise developing new materials and manufacturing processes to improve upon these properties.

The rise of AVs clearly represents a disruptive force to the tyre industry, breaking open new areas for development and innovation. This presents a great opportunity for tyre manufacturers to further push the envelope on tyre design to keep pace with a rapidly changing automotive industry.

Needless to say, an exciting future lies ahead for the seemingly humble tyre.