Bridgestone Corp.’s Blizzak studless tires have for the 16th consecutive year been the most popular tire choice for passenger cars in Japanese cities which see heavy snowfall. The tires possess overwhelming market strength in these cities, where they are installed on approximately half of all passenger cars. At the core of Blizzak tires is Bridgestone’s proprietary foamed rubber technology, which has continued to see improvements ever since it was first developed.
The latest version of this technology has improved the Blizzak’s gripping performance by adding new silica to its formulation, increasing the tire’s ground contact force while maintaining the active foamed rubber’s softness and ability to remove the water layer. This has worked alongside changes to tread patterns to reduce the tire’s braking distance on ice by 10 percent, further boosting peace of mind. Since the active foamed rubber used in Bridgestone’s existing Blizzak VRX was already highly technically advanced, surpassing that level has been both difficult and challenging, says Shoko Sugae, who is in charge of developing the latest version of Bridgestone’s foamed rubber technology.
Bridgestone arrived at the solution of adding small silica particles to the tire’s formulation through repeated trial and error, Sugae says. In the case of conventional silica particles, it was necessary to reduce the amount of friction modifiers blended to allow the silica to bind only to polymers contributing to grip force without being bonded to polymers contributing to pliability. As the latest version of Bridgestone’s foamed rubber technology uses smaller silica particles, the polymers can be fragmented more than before, and even when more friction modifiers are added, the particles effectively bind to polymers that contribute to grip force without binding to polymers that contribute to pliability.
As a result, Sugae says, the new tire’s tread is able to maintain its softness while effectively sticking to stick to the ice, which is the ground contact surface after water is removed. This has led to significant improvements in the tire’s grip performance.