Tweel designer Steve Cron honored at ITEC
AKRON — There’s no telling what will inspire the next big idea, the one that sends ripples — or maybe even waves — through the industry.
The International Tire Exhibition & Conference (ITEC), held Sept. 11-13 at the John S. Knight Center in Akron, is built around recognizing the ideas, both big and small, that are shaping the industry. And the Harold Herzlich Distinguished Technology Achievement Award, presented at each biennual show, honors the big ideas that brought the tire industry to where it is today.
This year, ITEC honored Steve Cron of Michelin North America Inc., who, along with his colleague Tim Rhyne, developed the Tweel, a design that combines a non-pneumatic tire with a polyurethane-spoked wheel.
The Tweel design that Michelin has brought to the market is miles away from where it began. It started out with the look of a pneumatic tire.
“We kept thinking in terms of thickening the sidewall or using better materials, until the end of 1997 when the light went off in my head and I said, ‘Ah. This is the wrong idea,’ ” Mr. Cron told those attending the event.
“The idea really needs to be to carry the load like the pneumatic tire does: From the top. We can do that by taking the budget of material, if you will, that we are using in the sidewall and you put it up in the beam,”
That was a tricky move, Mr. Cron noted, because the beam really needed to be exactly right. To work, it had to have the correct amounts of rigidity and flexibility.
So Messrs. Cron and Rhyne started with a pneumatic tire look, but designed it without a sidewall insert. Instead, a beam was created for the summit of the tire, and it consisted of two sets of plies with a layer of low hysteresis rubber in between.
In 2001, they designed and prototyped a set of non-pneumatic tires for a Chevy Corvette, which they then drove on a cross-country road trip. What they discovered on that round-trip journey was that the tires had a comfortable, quiet ride, while also demonstrating decent handling and high-speed management.
That was the good news.
In the end, the tires’ weight and inability to properly adjust to cornering made them unfit for the market.
“In a straight line, we could run for a long, long time,” Mr. Cron said, “but any kind of cornering and we would have eventual carcass compression fatigue.”
But they had an idea of how that may change.
Shortly before their cross-country trip, the partners had been asked to help out on another design project that involved engineering an insert for a run-flat tire design. The honeycomb, spoke-like design of the insert got them thinking outside the tire and led to the polyurethane spoked structure for which the Tweel is known.
By 2005, the combined non-pneumatic tire and spoked wheel concept had become the heart of the design, and Tweel has found its best applications in the off-the-road arenas such as the construction, agriculture and lawn care industries.
That’s not to say that passenger car Tweel tires are out of the question, but the design isn’t ready to meet the everyday demands required.
For Tweel, the process is a slow and steady one. But progress, Mr. Cron said, is embedded in patience.
“Let’s not waste all of our time trying to tackle the automotive solution today,” he said. “Let’s go down and do the things we can do now and do well and we can climb the curve.”