BMW Motorcycle K1200LT front and rear turn signal bulbs use a P21W size. The replacement chart covers 1998 to 2009 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The BMW Motorcycle K1200LT uses the P21W bulb type for both its front and rear turn signals across all model years from 1998-2009.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework, which governs lighting equipment used in Europe and numerous other markets worldwide.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is the standard power rating for single-filament automotive signalling applications.
The P21W uses a BA15s bayonet base. The "BA15s" designation refers to a single-contact bayonet fitting with a 15mm base width, distinguishing it from double-contact variants such as the BA15d.
Because the P21W is a single-filament bulb, it serves one lighting function per housing. This contrasts with dual-filament types, which combine two functions, such as braking and running light, within a single bulb.
The front and rear turn signal positions on the K1200LT share the same P21W specification, meaning a single bulb type covers both locations across the entire 1998-2009 production run.
The BA15s bayonet base is not interchangeable with the BAY15d or BAZ15d bases, which carry offset or indexed pins. Substituting a bulb with a different base configuration would result in an improper fit.
A 21-watt draw at 12 volts produces a current of approximately 1.75 amperes per bulb. This value is relevant when assessing circuit load or evaluating compatibility with aftermarket flasher relay units.