BMW Motorcycle K75S front and rear turn signal bulbs utilize a P21W size. The replacement chart covers 1987 to 1992 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21W is the sole bulb type specified for the BMW Motorcycle K75S across all listed model years, covering both front and rear turn signal positions.
The K75S uses the P21W for the 1987-1988 and 1991-1992 model years, with no variation in bulb type between those positions or years.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework used across European and many worldwide markets.
As a single-filament bulb, the P21W serves one lighting function per unit, which in this context is dedicated turn signal operation rather than a combined stop/turn role.
The P21W operates on a 12V electrical system and draws 21 watts, placing it in the standard signalling wattage range for motorcycle applications of its era.
The BA15s bayonet base of the P21W features a single locating pin on the base collar, distinguishing it from the dual-pin BA15d variant and making the two types non-interchangeable despite their similar physical form.
Because the front and rear turn signal positions on the K75S share the same P21W specification, a single bulb type services all four turn signal sockets on the motorcycle.