Say goodbye to roadside tyre changes. Thanks to special side-wall reinforcement, the BMW Z4 Roadster's standard run-flat tyres are capable of being driven a further 250 km even after a puncture. The benefits make themselves felt far beyond that. The need for a spare tyre is eliminated, reducing weight and freeing boot space on every single journey. In addition, the standard Tyre Pressure Indicator (TPI) warns the driver whenever there is a fall in tyre pressure.