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21/05/2018
Lighter than air (well, almost)!

Airless Tires future prospects

 

Airless tires: what’s happening? Recent studies by research agencies shed light on a sector that appears to be on the rise

Nicodemo Angì

Traditional tires are more than 150 years old and the first patents date back to the mid-19th century. Many inventors and entrepreneurs, such as John Dunlop and Michael Goodyear, in fact, came up with the idea many years ago and not much has changed since.

Currently, three types of tires cover the vast majority of the market: traditional tube and tubeless tires, solid tires – specifically designed for  professional yet undemanding use, for example trolleys, forklifts, prams and so on – and then airless tires. Tubeless tires can rightly be considered more reliable (lower deflation rate in case of puncture) than tires equipped with an inner tube, yet non-pneumatic airless models pave the way for new revolutionary designs and structures, not to be underestimated.

 

Advantages and future improvements

In these tires, in fact, the pneumatic effect of the casing and the air it contains, is replaced by an elastic structure which in turn replaces the sidewalls of a conventional tire and, in general, a good part of the rim incorporating the hub too. The tread, made with a traditional mix of polymers and additives, is the only part that recalls a traditional tire.

In a sense we should refer to them as NPTs or non-pneumatic tires seeing the total absence of air.

Their light weight and puncture-proof structure, makes them particularly suitable for a wide variety of uses. Moreover, manufacturing these tires should prove less complicated than their traditional counterparts and potentially able to employ a wide variety of materials including plastic, recycled electronic materials and even paper, wood as well as recycled rubber.

Among the many benefits, how could we not mention a potentially longer lifespan and the ability to cope with extreme tasks, normally associated with military or industrial vehicles. These are actually already been used: Michelin, for example, has been equipping garden tractors, small excavators, quads and golf carts with its Tweels for quite some time now.

In fact, as highlighted by Credence Research, Michelin, Bridgestone, Hankook, Sumitomo, Kenda, Toyo and many others - are currently developing this technology and we can expect a massive use of it on cars as well.

Obviously a number of improvements are also expected, for example, stability, rolling resistance, vibrations, noise level and the ability to maintain their characteristics even at high speed. In addition, another factor might be responsible for slowing down the development and adoption of such technology within the next few years. Several car manufacturers, in fact, are putting up quite a resistance as this would mean having to rethink entire braking systems and suspensions. 

 

Here are some figures

Another study seeking to shed light on the future of airless tires comes from Global Market Insights, which forecasts a 200 million dollars market in the near future with off-road, heavy duty and military sectors as the driving force. The lion share would belong to radials but bias ply structures are expected to grow at a compound annual rate (CAGR) of 9% thanks to a very favourable quality / price ratio. This projection assigns the largest share of revenues to the Asia-Pacific area, facilitated in part by the presence of major producers such as Sumitomo and Toyo. In second place, the USA, credited with 26% of revenues both for the demand for military vehicles and because Michelin intends producing its NPTs across the Atlantic.

The heavy duty vehicle share should level out at 27% of the market while off-road vehicles will grow with a CAGR of 9% as they are considered more resistant and comfortable.

As far as tire sizes, the market will be dominated by 21 and 25 inch models, but large 35 inch earthmoving tires are expected to grow in popularity and boast a 10% CAGR.

 

“Electric” impulse

The increased popularity of electric vehicles could serve as an “accelerator” in the diffusion of these tires and Toyota stands out as an example. According to Bloomberg Technology, the Japanese brand is looking with interest at airless tires and their ability to reduce the inherent weight of electric vehicles, whether fuel-cells or battery driven, and thus increase mileage.

Even if this technology will be ready for commercial use only in a few years, Toyota already unveiled a concept vehicle with airless tires and in-wheel electric motors during the 2017 Tokyo Motor Show. The fuel-cell powered Fine-Comfort Ride displayed a rubber tread surrounding an aluminium and plastic hub and Chief engineer Takao Sato, affirmed that the lightness of the airless wheel unit would compensate the weight of the in-wheel motors. To date, these wheels weigh like normal tires but it is believed that future developments might go as far as eliminating an extra 5 kg by 2025. Sumitomo Rubber Industries, which supplied the tires and is testing them on "Kei" minicars and on golf carts, stated that other Japanese companies are also interested, especially for smaller electric vehicles.

The time frame seems to be quite short, and Wako Iwamura, head of the five-year project for Sumitomo airless tires, declared that his goal is to have a commercial product ready by 2020. This technology, unlike Michelin’s Tweel, has not been tested on cars and manufacturers will have to work hard at "convincing" both car makers and the public that airless tires are at least equal to conventional products.

One of the most crucial obstacles to overcome is rolling resistance, currently 20% higher than normal pneumatic tires: this handicap must be thoroughly dealt with as such a waste is totally unacceptable for a vehicle that is called on to make the most of the Energy provided by their Li-ion batteries.

On the other hand, the cost does not seem to be an obstacle, in fact Iwamura stated that as things stand prices are comparable to normal tires.

The course, therefore, seems to have been set: even if initially airless tires will be destined to  more specialized uses, within a few years, driven by the relentless electrification sweeping through the automotive industry, they are expected to gain important shares also in mainstream markets.

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