This guide is written to hopefully explain the BSR run flat system fitted to the Toyota Rav4 T 180 and SR180 Many owners have bought their cars without knowledge of this BSR system so here I will try to explain what it is and the options for replacing it.. What is the BSR system? It’s a Run flat system that is different from other types where the sidewall of the tyres used is heavily reinforced so if a puncture or deflation occurs the car effectively rides on the sidewall BSR (Bridgestone Safety