Michelin's Tweel tire changes game, challenges industry

It started as a "what if," an idea in ink on a napkin. But what it's become is revolutionary.

With Tweel, Michelin took nonpneumatic tires from concept to prototype to practical. It brought to the market a very real, very relevant airless tire that found its niche in the off-road space.

In fact, Tweel has proven itself so relevant that just about every major tire maker is imagining its own version of airless tires and is looking for a niche market of its own.

Tony Marconi, vice president of Michelin Tweel technologies, isn't surprised that others are reimagining the nonpneumatic tire concept. He's proud of that.

"It valorizes the fact that we weren't crazy by entering into an airless tire market," Marconi told Rubber News. "It sort of legitimizes to our group executives that this airless tire thing has a real market. And the public, the consumers, are willing to pay for airless tires because they bring value."

Since its commercial launch 10 years ago, Tweel has ventured on neighborhood streets, gone off-road, over lawns, through warehouses and across construction sites. It has fitments for scooters, lawn mowers, side-by-sides, forklifts, golf carts, ATVs, military vehicles and construction equipment.

Yes, Tweel has come a long way in 10 years of manufacturing.

The Tweel concept really took root in 1997 when Tweel co-inventors Steve Cron and Tim Rhyne got a greenlight from Michelin to work in their spare time on the airless tire concept they had conceived.

And in the early in the 2000s, Tweel started to generate buzz. Still it would be more than a decade before the tire would go into manufacturing.

"It took us a while to decide: What are we going to do with this technology?" Marconi said.

And for good reason. With Tweel, Michelin was preparing to venture into unknown territories. It was simultaneously defining the market and gaining a better understanding of what the nonpneumatic tires could actually do. Because until that point, NPTs were seen as unneeded disruptive technology.

But Tweel proved it was something more. And Michelin, Marconi said, believed in the technology.

That's why in October 2014, the tire maker christened its 135,000-sq.-ft. Tweel manufacturing facility, located just outside of Greenville, S.C.

Initially—and somewhat naturally—Michelin looked at Tweel's potential in the automotive space.

"They ultimately wanted to go to market in the automotive sector because, obviously, it's a huge part of our business—it's probably where we sell the most tires in terms of quantities," Marconi said. "And it's where, when you personally reflect on flats, you think more about your car than maybe a commercial mower or a side-by-side. Cars are just so much more top of mind for us.

"But we knew that the technology wasn't really ready for the automotive application for a couple of reasons. There was no regulatory standards by which we could approve the airless tire and legally put it on the road and put it on the market. And secondly, we didn't know if the technology would be valorized enough by the general public to be willing to pay."

Because it turns out Tweels are more costly, at least at face value.

And that makes sense. When you replace air with a structure, you're adding materials costs that need be recouped. And while airless tires may offer some benefits that could potentially close that cost gap—such as its service life due to puncture resistance—it can be tough to convince consumers to pay more up front.

The biggest problem, then, was just that customers and consumers hadn't met Tweel. Once the public sees and experiences exactly what Tweel can do, they understand the value, Marconi said.

So Michelin ultimately opted to prove its product with skid-steer loaders and zero-turn mowers.

"That was two areas where, during the phase before we went to market, we had proven there was a very viable market," Marconi said. "We partnered with an OEM that validated for us this could be a game-changer in the commercial mowing industry. So, that was the market.

"It wasn't our ultimate goal. Our ultimate goal was to learn quickly about airless tires, about what value they bring. Is it a viable product? Is the performance sustainable? Can the design be scaled up or down, either in tire size or load and speed. And the idea was to continue to learn about the manufacturing and the technology so that we could move up the food chain, if you will, from commercial mowers to skid steers and on to bigger, heavier, faster things and approach the automotive industry. (That) was sort of the ultimate goal."

And in many ways, Michelin has done exactly that.

Tweel has gone from zero-turn lawn mowers to truck-mounted fork-lifts. It's ventured off-road with ATVs and UTVs. It's found fitments on golf carts and it has assisted first responders and aided the military in off-road arenas.

And all of the know-how has led to Uptis, a nonpneumatic tire that targets the automotive space.

"Uptis represents the birth of a new cousin or a sister product," Marconi said. "… Its form and function are largely the same, but it is basically adapting the design both through the manufacturing process and the materials to meet the automotive need, which is a little bit different from the off-road need."

One of the challenges that the nonpneumatic tire design brings to the automotive space—or any space, really—is around rolling resistance. Simply, pneumatic tires, when they are inflated properly, demonstrate better rolling resistance than nonpneumatics.

"Air is costless, which means it's free; it's massless, which means it doesn't weigh anything; and it's lossless, which means it has no hysteresis or it doesn't create any rolling resistance in the tire," Marconi said. "When we replace air with the mechanical structure, you are adding in mechanical structure that does degrade the rolling resistance."

That structure—the epitome of the nonpneumatic tire—makes the jump to the automotive space a tricky one, and it's something Michelin is still working to understand as it progresses with the development of Uptis.

But Tweel has embraced its uniqueness and found its perfect home off the road, where the tires tackle rugged terrain with ease. Much more easily than air-filled tires.

"Tweels are able to envelop obstacles, and when they do that they are able to deform and restore their shape and propel the vehicle forward," Marconi said. "They sort of push off of the obstacle like a runner coming out of the starting blocks. They are able to be equal or better in fuel economy than a pneumatic.

"A pneumatic tends to bounce over an obstacle because it's filled with air like a basketball, and when it bounces a lot of the energy goes up, and that is not in the forward direction of the vehicle. So (pneumatics) lose some of their stored energy on rough terrain to vertical motion, whereas Tweel envelops the obstacle and pushes forward so they retain that energy in a forward motion, and that helps Tweels be equal or better in rolling resistance on rough terrain."

It's exactly these qualities that has Michelin eyeing a new Tweel, one for wheelchairs.

"We think that Tweels can bring value to folks that are in wheelchairs, we think in a couple of ways," Marconi said, noting they hope to have a wheelchair Tweel product available next year. "We know that the solid tires—and even to some degree the pneumatics—can be pretty harsh to the rider on rough terrain. And we think that Tweels can bring some better compliance and damping to lessen those vibrations and impacts over rough terrain."

Really, you never know where Tweel might end up. Because it's proving itself again and again in markets and arenas nobody expected.

And as it does, Michelin learns more about its game-changing product.

"It's interesting, along the way, we didn't really have the strong desire to be in some of the markets that we are in today with Tweel," Marconi said. "But we found through this exercise that there really is a market in these off-road segments for airless tires."