BMW Motorcycle R850R front and rear turn signal bulbs use P21W size. The replacement chart covers 1995 to 2001 production years with 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 R850R across all listed turn signal positions and model years.
P21W is an ECE-standardized single-filament bulb rated at 12 volts and 21 watts, mounted on a BA15s bayonet base.
The BA15s base designation indicates a single-contact bayonet fitting with a 15mm base width, which is distinct from the dual-contact BA15d variant and the two are not interchangeable.
The single-filament construction of the P21W means it serves one switching function only, making it suited to dedicated turn signal housings rather than combined stop/turn applications.
The ECE standard classification indicates the P21W meets European and international regulatory requirements for signalling bulbs, covering output and color performance thresholds.
The R850R front and rear turn signals share the same P21W specification across the 1995-2001 model years, meaning a single bulb type services all four turn signal positions on the motorcycle.
At 21 watts, the P21W draws a defined current load that the turn signal flasher relay on the R850R is calibrated to recognize. Substituting a bulb with a significantly different wattage, such as an LED replacement without a load resistor or compatible relay, may cause incorrect flash rates.