By on October 30, 2017


Airless tires are one of those things that crop up every few years, but they never seem to stick around long enough to become commonplace. Already, certain construction vehicles use flat-proof rubber, and tire manufacturers have been playing with airless systems for some time. For example, Hankook has the iFlex, its fifth attempt at non-pneumatic tires, and Goodyear has actually begun selling airless donuts on commercial lawnmowers. Michelin even has a 3D-printed round that it claims will last the lifetime of a vehicle.

Unfortunately, nobody seems able to come up with a solution that works at higher speeds. While they’re great at taking impacts, the existing designs aren’t so good at coping with high levels of heat. But it’s not for a lack of trying — there may even be a breakthrough just around the bend, especially since everyone seems so interested. Rolling resistance and weight are two of the electric car’s worst enemies. If an automaker could mitigate those issues effectively, that would be another leg up on the competition.

It’s an issue weighing heavy on the top minds at Toyota at the moment. The company’s recent concept EV, the Fine-Comfort Ride, came equipped with a set of experimental airless tires from Sumitomo Rubber Industries, boringly named the Smart Tyre Concept-A. Toyota’s theory is that non-pneumatic tires, consisting of a solid band of rubber encircling lightweight alloys, could eventually compensate for the weight of wheel-mounted electric motors. 

The end result is better efficiency stemming from lessened rolling resistance and overall heft. However, the way Sumitomo tells it, the technology wouldn’t have to be limited to EVs. The company is approaching the airless-tire endeavor as a way to improve safety and free drivers from the plight of having to manage tire pressure. Sure, it’s focusing on the “mobility” angle and promoting the use of sustainable materials, because that’s what you do in 2017. But you could theoretically slap these babies on a 1993 GMC Sierra and burn all the gas you can afford.

But first, you’ll have to wait until they’re ready for market. According to Bloomberg, Sumitomo is only running them as test platforms on ultra-small Japanese kei cars and golf carts right now. So, exactly how long you’ll have to bide your time with ancient radials is up in the air. While Sumitomo intends to include some of the lessons learned in pursuit of non-pneumatic rubber on production tires within a few years, genuine airless tires aren’t anticipated until the latter half of the next decade. Wako Iwamura, head of the five-year airless-tire project at Sumitomo Rubber, said his personal goal is to have a commercial product ready by 2020 — though it wouldn’t be an all-weather application.

Currently, the concept tires weigh about the same as their aired counterparts, but Toyota’s chief engineer, Takao Sato, believes developments will eventually shave 11 pounds from each tire’s total weight by 2025. Interestingly, that’s just about the same time that most automakers plan to have fleet-wide electrification.

[Image: Toyota]

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23 Comments on “Everyone Is Working on Non-pneumatic Rubber for Your Future Car...”

  • avatar

    I enjoy Toyota’s C4 Corvette saw blades. That is all.

    • 0 avatar

      What about the name? The Toyota Fine-Comfort Ride. Next will be the badge-engineered Lexus Great-Grilled Conveyance.

      Too bad Scion died, or we could be looking at the Scion Super-Fun Mobility Creature.

    • 0 avatar

      Wouldn’t running those turbines the other direction push air through the brakes?

      • 0 avatar

        They’ve got it set up correctly, IMO. You want to push the air through the brakes on the passenger side, but pull the air through on the driver’s side. This helps to guide the vehicle away from oncoming traffic and into the ditch if the driver falls asleep.

        Some prefer a reversed setup to counteract the effect of the crown of the road, reducing overall steering and tire loads. I don’t think it’s ever worth compromising the safety of oncoming children for that convenience though. I believe the children are our future. Teach them about turbine wheels and let them lead the way.

      • 0 avatar

        They aren’t really turbines, it is set up so the rotating force allows the tire to flex instead if rip. They are directional, and should be facing forward on the opposite side as well.

    • 0 avatar

      Only that isn’t the wheel, it is the rubber tire.

  • avatar

    Every now and again these kinds of concept tires materialize. I’ve seen a dozen in my lifetime.

    Every one of them seems to be designed in the side view only. Hence the talk about rolling resistance, ride harshness and so on.

    I have never seen a concept that addresses the tire issue in plan view, that is, the view from above (or below) It is the tire’s distortion in the plan view that creates the “feel of the road”, or generates the slip angle that allows the driver to control the car. It is the twisting of the tire, in plan view, that provides most of the self centering force. And the amount of twisting, or slip angle, is a major determinant of understeer or oversteer.

    When I question show people about this aspect of the tire, they usually give me a completely blank look. When I bring this up to real tire and chassis engineers, they all laugh, not at me, but sat the concept.

    So, if this is really news, let’s have an explanation of how these tires work, in plan view. If they don’t, it’s not news, sand doesn’t deserve a space in TTAC.

    • 0 avatar

      relton – – –

      Thanks. I was waiting for someone to say that the Emperor has no clothes…

      For specialty vehicles (like front-end loaders) under ideal conditions (like warm sunny days), these may be a good idea.

      But don’t hold your breath for passenger cars driven under a variety of conditions in all climates. In fact, for those purposes, these things would have to be a disaster. Why? Well, here are ten very considerable issues – – –

      1) Thermal coefficient of flexibility (deformation) goes down with decreasing temperature much faster with airless tires than with a rubber-surrounding-an-air-balloon (pneumatic tire). If you can get a good ride on a road whose summer temperature is +120 deg F, what do you think your ride will be like on plastic vanes at -20 deg F?

      2) Don’t dare leave your car parked with one wheel in a deep puddle overnight in Winter. The thawed puddle may be refrozen overnight, after entering the spaces between the vanes. You may be literally frozen to the earth.

      3) We already have tires that are sufficiently puncture-resistant: they are called “run-flats”.

      4) What happens when you’re traveling on a gravel road, and not-so-little stones get wedged in among the vanes so that they abrade and brake the vanes as the car moves? And whet happens when these not-so-little stones are flung out at other vehicles when the car is traveling at speed?

      5) How does one clean adhesive brake dust out from among the vanes to “detail” your car for a Saturday afternoon cleanup? Simple flushing won’t do.

      6) How do vaned airless tires respond to off-road use in muddy fields or rock climbing when sidewall traction is critical? (Since there is no sidewall!)

      7) What selection of wheel types would be available, and would the local garage have the equipment to mount airless tires on any choice of wheels?

      8) What are the upper speed limits for these tires? 55 mph? 75 mph? And what would the NOISE generated by these tires be like at 65 mph?

      9) How would these designs respond to high-speed cornering and racing, such as on the Nürburgring?

      10) What would the weight, price, and longevity be for these airless designs? I’d venture that a conventional 80K-mile Michelin tire would last much longer, simply because of the mechanical fatigue-failure of the plastic vanes, if for no other reason.


    • 0 avatar

      Right, they’ve been making 4 wheeled cars for ever, until they come out with a 5 wheel car, its not news.

  • avatar

    Something tells me the ride will be terrible when they figure it out. Swapping out current “run flat” tires with conventional ones usually gives a big boost to ride comfort.

    I’d be happy if the automakers just stopped going to absurd sized rims as “standard” options. I don’t need a 20″ rim. It’s not good for handling, ride comfort, acceleration or fuel economy. It’s a silly styling trend.

    • 0 avatar

      I’m skeptical. They probably could have come up with something by now if they really wanted to.

      I don’t think the manufacturers want to replace pneumatic tires unless they can charge significantly more for the new technology. Why would they volunteer to diminish their profits? Flat tires, blowouts, bubbles, etc help the bottom line for the tire manufacturer, distributor, and retailer/service centers.

      I wouldn’t be surprised if the tire manufacturers themselves are pushing for ever bigger rims and tires while road conditions continue to get worse (in the US at least).

    • 0 avatar

      I agree. I think the giant wheels look ridiculous. Not to mention the $2k tire replacement in 30 months. Maybe it’s to fit giant brakes on modern vehicles approaching kiloton weights.

  • avatar

    No doubt the solution will be graphene.

  • avatar

    All I have to say is that I’ve always wondered what happened to the Uniroyal tires from a decade or so ago with puncture sealant built into the tire body. I remember Consumer Reports tested them and didn’t find anything wrong with their ride and wear resistance, and the self-sealing seemed to work fine even in the face of a ridiculous number of punctures.

    Seemed like a much better plan than an air compressor and a can of fix-a-flat.

  • avatar
    SCE to AUX

    Airless tires will appear at the same time as the cheap, durable, 5-minute charge EV battery.

  • avatar

    So how do they work on something where the tire pressures are different front and rear? Do you have to get s different “stiffness” for front and rear. What about cars that use the same tire as another car but at different pressures? How will they handle that or will they sell different stiffness like they do rubber compounds?

  • avatar

    As any long-time reader of Popular Science or Popular Mechanics can attest, this effort has been going on since solid-rubber tires were first used on wagon carts.

    The Michelin Tweel comes to mind.

  • avatar

    One word: Polyglas

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