Automotive Engineering, June 1993 v101 n6 p72(1) Rolling-core support for run-flat tire. (Bridgestone Corp.) (Tech Briefs) Jack Yamaguchi. Abstract: Bridgestone Corp has developed Roll-flat Support, a rolling core support for flat tires. The device, still in its prototype stage, is made of three of thermoplastic pieces and fi ts within a conventional wheel-tire combination in the aspect ratio range of 60 through 82. During one test, a sedan fitted with the Roll-flat Support travelled 200 km at 60 km/hour with its right front wheel deflated. Full Text: COPYRIGHT Society of Automotive Engineers Inc. 1993 Bridgestone has developed a run-flat device which Japan's largest manufacturer of tires and related components and equipment calls "Roll-flat Support." The device, still in its prototype stage (with further refinement continuing), fits within a conventional wheel-tire combination in the aspect ratio range of 60 through 82. Anything lower in profile would not have enough space for the new device. (Bridgestone is already marketing specific ultra-low-profile, run-flat tires with reinforced side sections.) The support, a wheel-like structure built up from three lightweight, thermoplastic pieces, rolls around the wheel. The support has a sturdy I-section with wider, lower base that comes into contact with the tire's inner tread when it is deflated, as in the case of a puncture. The rolling support generates virtually no friction between its outer periphery and the tire's inner surface, thus precluding damage to the latter. According to Bridgestone's own evaluation, it has little effect on the tire's basic performance criteria such as dry and wet handling, high-speed durability, comfort, and rolling resistance. In one test, an intermediate-size sedan equipped with the Roll-flat Support covered 200 km at 60 km/h with its right front wheel deflated, reports Bridgestone. Article A14347267