Making Tires from Weeds (Seriously)

There are few things more annoying for people with lawns than weeds. Particularly dandelions. Sure, when they flower with the yellow top they may look pretty. And what child can resist blowing the white, spherical seed heads, which helps distribute even more dandelions for the future. Try to pull a dandelion, and odds are good that unless you’re using a tool, you’re going to leave a whole lot of root in the ground. The tap-rooted perennial herbaceous plants of the species Taraxacum are nothing if not hearty survivors.

As Anita Sanchez, author of The Teeth of the Lion—The Story of the Beloved and Despised Dandelion, writes on the website of the Maine Organic Farmers and Gardeners Association (mofga.org), “Dandelions probably will never be eradicated, but we can learn to be more at ease with dandelions and other wild things—and maybe even to love them a little.”

At this point you are probably wondering how this story got into this magazine. A mix-up at the printer, perhaps? Somehow the copy for an agricultural publication got slipped into the automotive folio?

No, this is a story about dandelions.

And while Dr. Peter Zmolek, director of R&D, Continental Tire the Americas, may not love dandelions, he doesn’t find them to be a nuisance. In fact, he and his colleagues at Continental are working to find the ways and means to use dandelion roots—actually, the latex sap that is exuded from the roots—to make tires.

That’s right.

Instead of using rubber trees (Hevea brasiliensis, for those of a botanical bent), the Continental team, working with personnel from the Fraunhofer Institute, are sourcing the latex from a Russian dandelion (Taraxacum kok-saghyz) to make tires.

“One of the questions we often get is if it is the same stuff as we get from trees,” Zmolek says. “Generally it is.”

He explains, “We’ve spent a majority of our time on cultivating these plants to be ideal for application in tires.”

What they have developed is a material that they’re calling “Taraxagum” (see, even they are sticking with the Latinate approach). And they’ve produced a tire, a WinterContact TS 850 P, with it. Zmolek explains that winter tires actually need more rubber in them than other seasonal tires for purposes of grip.

(Why rubber at all for tires? Zmolek answers, “Think of a metal train wheel. The behavior of that wheel is different than that of a tire. For a vehicle to be comfortable, the flexibility of the rubber plays a key role.” Steel wheels aren’t exactly comfortable, which is one reason why passenger trains have serious suspension systems. “One thing our company stands behind is the safety of our tires. Braking performance is dependent on the flexibility of the material.” Which is why winter tires need more rubber than summer tires: the cold attenuates the flexibility. “If you have a hard material like plastic”—assuming that you’re not using rubber for tires—“and then put on the brakes, the vehicle would slide. Rubber grips.” He adds, “The macro-molecular structure of the street acts like sandpaper.”)

Given that rubber trees have been used for years, why change? Well, there are several reasons. One is that they grow in an area that’s ±30° of the equator. And one of those areas includes the rain forests, which are becoming increasingly unpopular as regards harvesting (although it should be noted that to obtain rubber, the trees are tapped, like maple trees for syrup). In addition to which: it takes about seven years for a rubber tree to be sufficiently mature for providing latex while dandelions grow like . . .). The tire market is growing at a rate of about 3% per year, so there needs to be an on-going effort to obtain more rubber. And there tends to be considerable volatility as regards prices on the rubber market.

Advantages of using dandelions rather than trees are many. Zmolek points out, “They’re easy to grow. Easy to harvest. And the abundance is high.” It is conceivable that abandoned urban areas could serve as fields (Zmolek and I are talking while he’s in down-town Detroit, and one wouldn’t need to go far to find plenty of acreage ripe for the planting). He does point out, however, that they’re making sure that there wouldn’t be a problem with a neighbor’s lawn becoming infested with what are still weeds. Unlike trees, the dandelions can be grown in reasonably sized greenhouses.

Another consideration: logistics. Given where the latex is currently sourced and where tire plants are, there is a considerable amount of transportation required. “If you can plant outside your rubber-refining facility, there is literally no trans-portation cost,” Zmolek says. “In terms of performance, the material is on par or better than the material from rubber trees,” he says. Much of the work now is focused on establishing fields, regulating the harvest, and under-standing what happens if there are low yields: realize that this is a new model, not something well-established like the conventional rubber industry.

Zmolek says that the dandelion approach is truly sustainable, and points out, “Sustainability is not equal to green. Sustainability has three pillars: economic, environmental and social.” The use of dandelion root rubber can tick off all three.