Describe your tires to me. Don’t make this weird.
Did you respond with “rubber, they have those little ridges on them which I guess is for traction maybe?, and full of air”?
Well, first, “filled with air” is usually replaced by the word “pneumatic” in the auto industry, so learn the lingo, and now that we live in the future, you might just be wrong about your four wheels.
The “Race” to Airless Tires
Don’t worry, I hate my own puns just as much as you do.
Non-pneumatic tires have a lot of advantages over the industry-standard pneumatic tires of today. Instead of trying to make them puncture-proof or run-flat, airless tires can be punctured indefinitely as long as the structural integrity of their spokes isn’t compromised. They can also be made to weigh significantly less than pneumatic tires. Rubber is heavy, and so is compressed air. I mean, one of the main obstacles in hyper-speed trains systems is that they build up so much compressed air pressure that the air slows them way down. Compressed air in a container like a rubber tire also increases structural stress; if something presses up against the side of your tire, that pressure expands outward in all directions and stresses the rubber of your tire. With an airless tire, something pushing on the side doesn’t affect the integrity of the spokes, unless it actively is pressing against the spoke itself.
Michelin Leads the Way
So way back in the dark ages of 2005, three full years before Breaking Bad premiered (what did we used to watch?), Michelin invented and subsequently forgot about a design for an airless tire called a “Tweel“. I’m not going to call it that on subsequent references because I refuse to stoop to their level (“Tweel”? Really?). The combination tire and wheel is made from four component parts: a metal hub, a section of polyurethane spokes, a shear band surrounding the spokes to evenly distribute the load on the wheel, and the tread band, which looks like your average tire’s treads.
The Michelin airless tire still hasn’t caught on commercially. For one thing, it was debuted as a potential wheel for the Segway, and we’ve all seen how those fly off the shelves. For another thing, it wasn’t a marked improvement over current tires. They were just as heavy as regular pneumatic tires, but they were incredibly noisy due to the vibration of the polyurethane spokes, and they generated greater friction, although it was still in an acceptable range.
It has, however, caught on with construction companies as a cheaper alternative to their enormous pneumatic tires.
Enter the Spiro-tire
Bridgestone would not stand aside and watch the French beat the US at making car parts, so they joined the race as well, albeit 6 years after Michelin. The most major change in Bridgestone’s eerily nameless tires was that they had spokes coming off the hub that flow both ways. These spokes are also referred to as “thermoplastic”, which is probably still urethane, but I can’t be sure. It just sounds comic book-y. The utility of having spokes going both ways instead of just one prevents twisting or rotation of the treads, which could greatly affect handling and safety.
Wired.com also makes one of those so-obvious-it’s-troubling observations that these tires are always presented without sides. If they were to fill with dirt, they would be as useless as a flat pneumatic tire, so what would be the point?
Hankook Kicks Out the Spokes
Pictured at the top of this article, the Hankook i-Flex (how they’re not getting slapped by Apple, the copyright holder of “i” is baffling to me, but whatever) takes the technologies that Bridgestone developed for their airless tires and runs with it. Their tire is the best of all possible worlds, on paper at least. It eliminates all the empty space issues of Bridgestone and Michelin’s tires, while remaining airless and making it incredibly difficult to get a flat. And by “incredibly difficult”, I mean you’d have to leave it in the hot spot from that building in London that’s killing cars.
The other major benefits of the i-Flex are that it’s 95% recyclable (and hopefully that means it can be turned into useful things and not just that weirdly sproingy turf for playgrounds), and that it is shown to enhance fuel economy. It achieves greater fuel economy by being made out of lighter materials, and less weight means it takes less gas to get you where you’re going. It also has shown itself to be quieter than your standard pneumatic tire, which has become increasingly important in these times of fully electric cars that don’t have engine noise to cover up road noise.
The Future of the Road
Are airless tires the next big thing? Or are manufacturers married to the idea of improving on an existing property instead of focusing on innovation? I think airless tires are the way of the future, but I think they’re going to have to roll over a lot of things in their way to find widespread implementation. Here’s hoping that by the time Tesla completes its network of chargers for their electric cars, we’ll get quieter tires like these to keep our rides smooth. Fingers crossed.