The Bridgestone B380 RFT is a Passenger All-Season self-supporting run flat tire designed specifically for use on the Toyota Sienna minivan. The B380 RFT was developed to provide extended mobility when flat and provide year-round traction, even in light snow.On the outside, the B380 RFT features a symmetric, independent, siped block tread design that uses an all-season tread compound to provide traction on dry, wet and light snow-covered roads. Internally, the B381 features twin steel belts reinforced by a layer of nylon to stabilize the tread area and a rayon cord body to help withstand the punishment of being driven on while flat.