Bridgestone also operates a 281-acre research farm, the Agro Operation Guayule Research Farm in Eloy, Ariz., which is devoted to various aspects of cultivating guayule, a desert shrub native to Mexico and the southeastern U.S.
Building the tires was less important than creating the process that allowed them to be built, according to Niaura.
“It's a continuous process, not a batch process—the materials go in one end, and the product comes out the other,” he said. “We have no firm date for building the next guayule tires, but it's not a question of what's next—it's a series of nexts. We're learning how to influence the process.”
One of the major parts of that process is developing guayule rubber into a commercial product, according to Niaura.
This is an even more complex undertaking than it sounds, because there are many different types and grades of guayule. There are various grades of Hevea rubber, with different properties that make each appropriate to a certain part of a tire, and the same is true of guayule rubber, Niaura said. In any case, further research and development is needed in this area.
“We had some head start in this research, because we know how guayule behaves,” he said. “But it too is an ongoing process. I would expect there will be a need at some point to develop international standards for guayule rubber. There will be many different grades of guayule rubber and also many different guayule rubber producers.”
Research on guayule plants is ongoing in many different areas, including germplasm, yield and methods of seeding, Niaura said. Bridgestone has planted guayule fields all across Arizona, at varying altitudes and in different soil and moisture conditions, to determine which strains do best under which growing conditions, he said.