Reinforced sidewalls allow the tire to be driven "flat" for a distance specified by the manufacturer (usually 50 miles). RSC (inside a circle): BMW runflat system component[23] RWL: Raised white lettering Examples of different tire sidewall markings Star: Original tires for BMW TL: Tubeless TT: Tube-type, tire must be used with an inner-tube VSB: Vertical serrated band WSW: White sidewall SFI, or Inner: side facing inward; inside of asymmetric tires SFO, or Outer: side facing outward; outside of asymmetric tires SL: Standard load; tire for normal usage and loads TPC: General Motors OE fitments[23] TWI: Tread wear indicator – a device, such as a triangle or a small Michelin Man icon, located where the tread meets the sidewall, and indicating the location of the raised wear bars in the tire tread channels – TWI is also used to refer to the raised wear bars themselves.