BMW 325 front and rear side marker bulbs utilize a 12961 bulb size for both locations. The replacement chart covers 1986 to 1988 model 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 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, fitted with a W2.1x9.5d base. It operates at 12 volts and draws 5 watts.
The T10 designation refers to the bulb's tubular shape, with the number indicating its width in eighths of an inch. The W2.1x9.5d base is a wedge-type base, meaning the bulb is held in its socket by the tension of the base itself rather than by a separate locking mechanism.
The BMW 325 uses the 12961 bulb across both the front and rear side marker positions for the 1986-1987 model years.
The front side marker of the 1988 BMW 325 also uses the 12961 bulb, making it consistent with the two preceding model years for that position.
Because the same bulb size is specified for both the front and rear side marker positions, the 12961 is interchangeable between those two locations on applicable model years.
At 5 watts, the 12961 is a low-output bulb, consistent with its role as a marker light rather than a primary illumination source.