BMW Motorcycle R1100RS front and rear turn signal bulbs use a P21W size. The replacement chart covers 1993 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 R1100RS uses the P21W bulb type for both its front and rear turn signals across all model years from 1993 to 2001.
The P21W is an ECE-standard bulb, meaning it conforms to the Economic Commission for Europe regulatory framework used in European and worldwide automotive lighting applications.
P21W bulbs operate on a 12-volt electrical system and draw 21 watts, which is the standard wattage for single-filament turn signal applications in this class of vehicle.
The P21W uses a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single contact at the base, distinguishing it from dual-contact variants.
Because the P21W is single-filament, it serves a dedicated signalling function and is not wired to perform a secondary role such as running light or brake light duty within the same housing.
The identical bulb specification across both the front and rear positions means a single P21W bulb type covers all four turn signal positions on the R1100RS, with no positional variation in the fitment requirement.
The BA15s base is not interchangeable with the BA15d base, which carries two offset contact pins at the bottom rather than one. Substituting a dual-contact bulb in a single-contact socket would result in incorrect fitment.