Toyo Tire & Rubber Co Ltd exhibited a tire that does not need to be inflated Sept 8, 2017.
The tire, "noair," uses a plastic spoke in place of a rubber tube that stores air and reduces vibration, impact, etc. Five years have passed since Toyo Tire & Rubber exhibited a prototype of the tire at Automotive Engineering Exposition 2012 in May 2012. This time, by improving the structure of the spoke, etc, the company improved its durability by more than 700%.
The tire has a structure whose tread rubber (an area in contact with the ground) is integrated with the plastic spoke. The tread rubber was made with a rubber compounding ratio equivalent to that of the company's "Nanoenergy" series of fuel-efficient tires.
A thermosetting resin was used for the plastic spoke, and carbon fiber-reinforced plastic (CFRP) was applied to the outer ring, which is connected with the tread rubber and requires a high durability. It corresponds to the belt material of a common air-containing tire and improves the rigidity of the tread.
Toyo Tire & Rubber also used a plastic for the spoke of the prototype announced in 2012. However, this time, the company greatly changed the shape of the spoke, from an oval shape to an X shape.
"By referring to the shape of a foldable chair, we improved the durability by 700%, compared with the previous prototype," the company said.
Toyo Tire & Rubber increased the number of spoke bars from 20 to 100 in the aim of dispersing the ground contact pressure. Also, the company reduced rolling resistance by more than 50%, compared with the previous prototype, so that the performance of the tire becomes equivalent to that of tires that the company mass-produces.
Despite the improved durability, Toyo Tire & Rubber said, "There is no commercialization in sight. We need not only to establish standards for tires that are completely different from conventional tires but also to reduce noise and upthrust that passengers feel at the time of driving the vehicle. And cost reduction is also a big challenge."
"We are considering using the tire not only for four-wheeled vehicles but also for special-purpose vehicles," the company said.
Toyo Tire & Rubber is planning to start volume production for special-purpose vehicles, for which price limitation is small, and expand the application of the tire to four-wheeled vehicles.