Next-generation airless tires, pros and cons
Everyone probably already heard about the development of new airless tires, almost all of the world’s leaders have already presented their prototypes (for example hankook, about this we wrote an article on our website). Each motorist openly or secretly dreams about the tire, which will not be damaged after hitting a broken glass, a screwdriver, a nail… In fact, it will not be necessary to go to the nearest tire fitting shop and “fix” hands of local workers. Not to mention the tires with Runflat technology, which producers, in any case do not recommend any repairs after serious damages. So let’s consider whether the appearance of a universal tire is real in the nearest future, what are the pros and cons at this stage. Let’s go! A little history Like almost all new technologies, the airless tire was originally created for military purposes – the Pentagon understood that armored rubber did not always solve all safety issues. The first prototype was soon introduced and was tested on the American Hummer.
This prototype used a hollow design, with rubber partitions taking over the air function.
Which design? At this point, there are 2 main designs distinguished: -one filled with special fiberglass -the other compensates for the lack of air by the presence of polyurethane spokes-walls
In the first case they are most often made closed, so that the fiberglass is not lost on the road, but practice has shown more advantages of just an open system: less material, easier to manufacture, any resulting defects are much easier to notice. The design in the end seems very simple: the edge of the tire is a stretch clamp, in the middle – the classic hub, to which the spokes of polyurethane are attached in a strictly defined sequence. The resulting “pattern” of each modern manufacturer is different, each of them will demonstrate its advantages and disadvantages.
Advantages and disadvantages
Now let’s consider the most important thing, namely the advantages and disadvantages: 1) Airless wheel is able to change shape depending on irregularities – potholes and bumps are literally “swallowed”. 2) The wheel is fully functional as long as at least 70% of its elements are in place (which cannot be said about pneumatic rubber). 3) There is no need for pressure testing, and where there is no pressure, there is no possibility of bursting either. 4) The weight of an airless tire is much less than a classic tire. No need for rims (steel, cast, forged, etc.) reduces unsprung mass, which also results in positive driving effects for the vehicle. 3) No need to carry additional tools such as a jack, pump, wrenches… (however, the latter will be useful in any case) 4) Reduced transportable weight and, as a result, reduced fuel consumption! 5) The cost of airless tire (when they fully appear on the shelves) is unlikely to be higher than pneumatic counterparts, of course after the first period. 6) Eventually, the installation of airless tires will be available on absolutely any car. 7) Promising now the development of airless tire – the ability to quickly change the worn (or unsuitable for the current road situation) the top layer directly in contact with the road. I have to – install the “racing” profile, fix it with special bolts – and go. It is necessary to go to mountains – you may fasten high-profile “skin” on the same polyurethane basis.
As we see, there are a lot of advantages, but it is necessary to note the following disadvantages:
1) Unfortunately, so far the safe speed limit is 80 km / h. 2) Many constructions are still showing excessive noise and heating during a long speed operation. 3) Low load capacity of such a tire… It is necessary to improve the technology. 4) The stiffness of the construction is not adjustable. There is no possibility to take down the pressure and drive on sand and gravel.
So we wait, believe and hope! For now we have to be satisfied with only air tires, which, by the way, are also constantly improving! And where to buy them – everyone’s choice. From my part, I’m ready to recommend an online store xkontinent.ru/ – not only the most democratic prices, huge selection and delivery throughout Russia, but also the “tasty” shares, regular drawings of smartphones, CASHBACK and stuff. Service at the top, managers are professionals in their business, will help you find the best tires for your needs!
On airless rollers, or What tire manufacturers were going to captivate, but still have not captivated the customers
It’s not easy to find something more conservative than tires among car parts, components and assemblies. Despite the fact that every year tire manufacturers present new models, which seems to indicate that the tire industry is not standing still, since the transition from diagonal to radial tires and the refusal of the tube no significant changes have happened in the design of tires.
If tire manufacturers occasionally mention some new developments, later it turns out that, for example, behind the sonorous names Michelin Acoustic, Goodyear Sound Comfort or ContiSilent is only gluing to the inner surface of the tire strips of polyurethane foam, which reduces the noise from rolling tires.
The fact that such a constructive innovation increases the weight of the tire and, of course, its cost is somehow omitted.
The real usefulness of tire printing, which allows applying color drawings on the sidewall of the tire, you will not understand at all until you read in the manufacturer’s abstract that such tires in addition to satisfying the aesthetic needs of consumers distinguish the car in the dark, and thus contribute to safety.
However, in general the efforts of the developers are aimed, firstly, at the search for new materials to replace natural rubber and refined products used in the manufacture of tires, and secondly, at improving the tread pattern. Both tasks are of course important, but they do not promise significant design changes, and the reason why all the forces of the R&D departments of tire companies are thrown into their solution is probably due to the list of functional duties of tires.
To provide traction, to absorb and withstand longitudinal and lateral loads during driving and maneuvering, as well as to absorb shocks from wheel contact with road unevenness and thus contribute to flotation, stability, handling, ride comfort and durability of chassis components – no more is required from car tires.
Pneumatic tires are perfectly capable of handling these duties. And there would be no claims to tire manufacturers, if exactly 20 years ago they had not demonstrated to the public an airless tire, which is strikingly different from the “pneumatic” by design and benefits from use, and promised that by 2007 it would go into production. It’s 2017 – it’s time to ask: where is what was promised?
We were promised the following: two rings connected by flexible polyurethane spokes, the outer being a tread and the inner being to fix the tire on the rim. Is it necessary to explain why such a construction, unlike the “pneumatics” is not afraid of punctures, does not need to control the air pressure inside and does not require pumping if this pressure for some reason became below the norm? However, as the developers assured, apart from the most obvious advantage for users, the airless tires had other advantages.
When Michelin company which made the airless “porridge” announced that the Tweel tires developed by it are about 20 times lighter than conventional tires of the same size, it caused a wave of enthusiasm in the ranks of fighters for saving fuel and reducing the impact of its combustion on the environment.
It is well known that the energy generated by the engine is used to overcome the forces that prevent the car from driving. Among the things that have to be overcome is the inertia of the mass of the car itself, when it accelerates during acceleration, and the inertia of the mass of the spinning wheels during acceleration. The lighter the car and the wheels, the less power is taken away, and therefore less fuel is needed to produce it.
The flip side of the same coin is that the lighter the wheels, the easier it is to brake them when you need to slow down the car. And when the car itself has also become lighter, it can’t help but reduce the amount of braking distance.
The load on the working mechanisms of the braking system and, of course, on the engine, transmission and running gear are also tied to the weight. They also become less, which should have a beneficial effect on reliability and durability. However, the wheels are not only rotating, but also the unsprung weights. If their weight is reduced, then the smoothness of the car should improve.
Finally, it is worth mentioning that the announced by Michelin resistance of Tweel spokes to forces, acting on the car in transverse direction, was five times higher than the indicators of the sidewall carcass of conventional pneumatic tires. How it should improve the resistance to lateral drifting while maneuvering and increase the accuracy of car control, it is clear without any extra words.
It is puzzling how with so many advantages airless tires have not been mass produced so far and if they turned out to be interesting for someone, it is only for the manufacturers of military and quarry equipment, which are principally interested only in the fact that such tires are not afraid of gunshot holes and punctures, and all the rest does not matter at all.
There are different versions about it, but it is also a fact that the airless tires designed for ordinary motor vehicles have not been forgotten by the tire manufacturers. This is evidenced by the events of recent years, during which such designs were presented by Bridgestone, Hankook, Kumho and Yokohama.
However, Hankook Motiv and Kumho Maxplo consider the idea of changing wheel treadway depending on road conditions and driving conditions. In Motiv, tread blocks react to changes in road conditions by moving vertically, in Maxplo – by moving apart to the sides.
Moreover, to improve traction in icy road conditions, the Maxplo’s tread blocks extend out of the tread, but in both cases, the implementation of the conceived requires the tire to have an airless design, which forced the developers to turn to it. The features of Motiv and Maxplo indicate that such tires are a long way away from mass production, if they ever get there.
However, Bridgestone AirFree, Hankook iFlex and Yokohama Youmyaku are quite another matter. And it is possible that Bridgestone’s admission that the maximum safe driving speed of the AirFree does not yet exceed 60 km/h, just sheds light on why the design, whose production does not promise any technological difficulties, has not yet got rid of its conceptual status.
But may be the cost is the main problem? The above mentioned companies, presenting their airless developments, as if in conspiracy, keep silent about it or evade a concrete answer, which gives rise to assumptions that the transition to the production of airless tires is not profitable for the tire industry in terms of profit and threatens the economic turmoil. The situation is similar to alternative energy sources, which everyone advocates, and oil production, on the price of which the well-being of the world economy depends.
Again, the transition to airless tires not only affects interests, but also threatens the existence of the industry that was born with pneumatic tires. We are talking about tire shops and companies that produce tire equipment, tools and materials for tire service and repair. People employed in this industry are moving the problem of introducing airless tires into mass production from the technical to the social sphere. These are not all the reasons why the question remains open when the car owners will be able to assess what airless tires provide in practice, but not from the words of their developers.
Sergey BOYARSKIH Photo by the author and from open sources of ABW.BY
