TOKYO—Bridgestone Corp.'s "Uni-T AQII" technology—featured in the line of Potenza performance tires being launched in the U.S. this spring—is an extension of the company's basic tire technology designed to prevent the deterioration in ride and noise characteristics during the life of a tire.
The new extended-life benefits are in addition to features the company introduced to its tires three years ago to prevent a deterioration in wet-surface performance, Bridgestone said.
The Tokyo-based parent company of Bridgestone/Firestone Inc. originally launched its Uni-T AQ—for unified theory/advanced quality—in 1997. In Japan and Asia, the technology is known as Donuts, or Donuts AQ, with Donuts standing for "Driver Oriented New Ultimated Tire Science."
Bridgestone said it has sold more than 100 million tires worldwide that incorporate the Uni-T and Uni-T AQ technology.
The primary technological advance in Uni-T AQ resulted from work on the mechanism of rubber hardening, Bridgestone said.
In Uni-T AQII, Bridgestone engineers have addressed additional factors that figure in that mechanism, the company said, enabling them to reduce the increase in noise and the deterioration in ride comfort that occur during the life of a tire.
The engineers also have achieved further progress in preventing deterioration in wet-surface performance, Bridgestone added. Uni-T AQII also includes improvements in new-tire performance resulting from advances in roundness, compounding and manufacturing.
Altogether, the improvements achieved in the latest technology are attributable to six technological advances—four of which improve new-tire performance, and two which reduce deterioration in performance.
The first of the four advances for improving new-tire performance is Bridgestone's "adaptive contact blocks," which optimize the contact surface of each individual block in the tread pattern to maximize tire roundness under the pressure of contact. Bridgestone has used an improved version of its optimization technology GUTT (Grand Unified Tire Technology) to optimize the tread block surface.
The second advance in Uni-T AQII for better new-tire performance is New Long Linkage (L.L.) Carbon. Bridgestone said Uni-T improved tires' wear characteristics by linking the particles of carbon black into long chains.
However, making the chains even longer would have promoted bonding between the carbon and polymers and thus would have worsened rubber hardening, the company said. New L.L. Carbon includes technology for preventing that bonding, and therefore allows Bridgestone to improve wear resistance by lengthening the carbon chains.
A third advance that has improved new-tire performance is "aqua powder," a new, undisclosed additive to the rubber compound. Bridgestone claims aqua powder is even more effective in some cases than silica additives in improving wet-surface performance.
The fourth advance for better new-tire performance is "riblet walls." Bridgestone forms tiny riblets along the sides of the grooves in the tire tread. That, it claims, promotes smooth flow of water and thereby helps prevent hydroplaning.
Progress in reducing performance degradation is attributable to AQ Compound II and Tread-on-Tread.
AQ Compound II is a combination of three technologies for preventing the rubber hardening that occurs gradually in tires. That maintains wet-surface performance and also maintains a quieter, smoother ride.
The three technologies for preventing rubber hardening are a special softening agent, an agent for preventing repolymerization, and an agent to prevent sulfur rebridging.
Tire rubber contains oil, which tends to migrate during the life of the tire to the portion under the tread, Bridgestone said, causing the tread portions that lose oil to get harder. Bridgestone has replaced the conventional oil with a substance that comprises larger molecules which migrate less easily through the rubber.
As for repolymerization, the heat and deformation that occur when a tire rolls under a load break the polymers in the rubber, Bridgestone said. The polymers take a chain reaction to make long chains, which harden the rubber. So Bridgestone's new agent for preventing repolymerization thus helps maintain rubber softness.
The new agent for preventing sulfur rebridging offers a similar benefit. Tire rubber hardens as heat promotes the bonding known as rebridging between the sulfur and polymers.
Tread-on-Tread, meanwhile, refers to a combination of rubber compounds in the tread.
In Uni-T AQ, Bridgestone employed base rubber that provides especially high grip. The base rubber extends up through the cap in conical projections. As the tread cap wears, a progressively larger area of high-grip base rubber becomes exposed. That helps prevent the deterioration of performance on wet surfaces.
In Uni-T AQII, Bridgestone has improved new-tire performance on wet surfaces by exposing the tips of high-grip base rubber initially. The cap rubber covered the base rubber completely in previous Uni-T AQ Tires. Bridgestone also has increased the amount of base rubber, which helps maintain wet-surface performance longer.