The Potenza RE050A I RFT (Run-Flat Tire) is Bridgestone's Max Performance Summer run-flat tire developed exclusively for selected BMW Z4 vehicles, as well as 3 Series cabriolets, coupes and sedans equipped with BMW's sport package. The Potenza RE050A I RFT is designed to provide temporary extended mobility for a distance of 50 miles at up to 50 mph even after a puncture has allowed complete air pressure loss. The Potenza RE050A I RFT is also designed to combine responsive and predictable handling with good traction on dry and wet roads. It is not intended to be driven in near-freezing temperatures, through snow or on ice.The Potenza RE050A I RFT features a high-grip tread compound molded into an asymmetric tread design. Stable outboard shoulder elements, intermediate tread blocks and a continuous center rib provide responsive handling, high-speed stability and traction on dry roads, while circumferential and lateral tread grooves pump water out from under the tire's footprint to minimize hydroplaning and aid wet traction. A continuous rib adjacent to the inboard shoulder promotes even wear and resists inside wear generated by suspensions that specify negative camber alignment settings. The tire's internal structure includes twin steel belts reinforced by spiral-wrapped nylon to stabilize the tread area and enhance handling, high-speed capability and ride quality. The structure of the Potenza RE050A I RFT also features Bridgestone Side Support Run-Flat technology reinforced sidewalls to support the vehicle after a puncture causes a loss of air pressure.Install Bridgestone Potenza RE050A I RFT tires in sets of four only.Due to the traction and handling capabilities of the Potenza RE050A I RFT, Bridgestone recommends Potenza RE050A I RFT tires only be used in sets of four to provide the best handling characteristics and tire performance. Potenza RE050A I RFT tires may NOT be mixed with other tire models, such as the Potenza RE050A RFT or Potenza RE050A II RFT.