NASHVILLE, Tenn.—Frustrated with having to discard worn-out solid industrial tires, a Japanese industrialist has tinkered with the basic solid tire and come up with a way to salvage the tire core by using a replaceable tread cover. Calling his invention ``Soft Tire,'' Japanese businessman Muneyasu Fukunaga now is looking for a manufacturer and distributors for the re-coverable solid tire.
Mr. Fukunaga, owner of a steel recycling company in Osaka, Japan, claims to have worked on the concept for more than 15 years, and now has the design patented in 17 countries, including the U.S. His company, Fukunaga Engineering Co. Ltd., displayed prototype versions of the Soft Tire at the recent International Tire and Rubber Association trade show in Nashville.
Arguing that only 25 to 30 percent of a solid tire's weight is worn away before it normally is taken out of service, Mr. Fukunaga focused on ways to salvage the remaining 70 to 75 percent of the rubber that makes up a solid tire's base—or core, as he prefers to call it.
Mr. Fukunaga's basic idea was to make the core robust enough to last at least five or six years, or the life of an average forklift truck. This means a single core would be re-covered a dozen times or more.
To provide for mechanical grip between the core and cover, Mr. Fukunaga designed the core with circumferential grooves and the cover with circumferential ridges, so the cover slots into the core.
During its average six-year life, Mr. Fukunaga said, a forklift truck will go through 36 solid tires.
By comparison, Mr. Fukunaga said he expects the same truck would use 48 Soft Tire covers but only four cores—yielding a 62-percent savings in material and a 50-percent reduction in energy used in manufacturing.
Being able to design the core and cover separately will allow engineers to better tune the Soft Tire for specific applications, the Japanese inventor said.
Mr. Fukunaga described the Soft Tire's ride as better than a solid but not quite as good as a filled pneumatic.
The prototypes displayed in Nashville were built by a Chinese company under contract to Fukunaga Engineering.