BMW Motorcycle R1100RT front and rear turn signal bulbs use a P21W size. The replacement chart covers 1994 to 2001 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 BMW Motorcycle R1100RT uses the P21W bulb type across all listed model years for both front and rear turn signals.
The P21W is an ECE-standard single-filament bulb rated at 12 volts and 21 watts, designed for signalling applications such as turn signals.
P21W bulbs use a BA15s bayonet base, which is a single-contact bayonet fitting with a 15mm collar width.
The BA15s base is not interchangeable with the BA15d base, which carries two contacts. Substituting a dual-contact bulb in a single-contact socket results in incorrect fitment.
The R1100RT front turn signal position takes the P21W across the full 1994-2001 model year span covered in the specifications.
The rear turn signal position on the R1100RT also takes the P21W across the same 1994-2001 span, making the front and rear positions share an identical bulb specification.
The ECE designation on the P21W indicates the bulb conforms to United Nations Economic Commission for Europe regulations, a standard adopted across Europe and numerous other markets worldwide.
At 21 watts, the P21W produces a relatively high output for a single-filament signal bulb, which is a characteristic that distinguishes it from lower-wattage parking or position bulbs that share the same BA15s base.