BMW Motorcycle R45 headlight bulbs utilize a 9003 size for both high and low beam functions. The replacement chart covers 1978 to 1985 production 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 R45 uses the 9003 bulb size for both the high beam and low beam headlight positions across all listed model years, 1978-1985.
The 9003 is an ANSI-standard halogen bulb recognized in the United States and Canada, operating on a 12-volt electrical system with a dual-filament design rated at 60 watts for high beam and 55 watts for low beam.
Because the 9003 contains both filaments within a single housing, one bulb serves the high beam and low beam functions, which is reflected in the R45 specifications showing the same bulb size for both positions.
The 9003 uses a P43t base, a bayonet-style mount with a 43mm collar, and fitment depends on this base type matching the socket in the headlight assembly.
The 9003 bulb is sometimes marketed under the designation HB2 or H4, and these designations refer to the same bulb type, differing only in the naming convention used by the manufacturer or region.
Substituting a single-filament bulb in place of the 9003 would not satisfy both beam functions simultaneously, as the dual-filament design is integral to how the headlight assembly operates on the R45.