Triumph Spitfire Parking Light Bulb Size

The Triumph Spitfire parking light uses bulb sizes 257, 1157, and 1895 depending on the specific version of the vehicle. Data for the components covers the range from 1973 to 1980.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1980	257	257	Check Price
1976-1979	1157	P21/5W	Check Price
1973-1975	1895	1895	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Festoon or BA9s base instrument bulb. 12V, 2W.	257	Check Price
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157	Check Price
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W	Check Price
ANSI standard (US & Canada). Miniature wedge bulb (T5). 12V, 0.9W.	1895	Check Price

Other Locations

Additional Notes

The 1157 bulb is the most frequently specified parking light bulb across the Triumph Spitfire data, covering the 1976-1979 model years. It is a dual-filament type with a BAY15d bayonet base, rated at 12V and drawing 21W on its primary filament and 5W on its secondary filament.
The dual-filament design of the 1157 means a single bulb serves two lighting functions simultaneously, which is why it appears in parking light applications where combined stop and tail functions are common.
The 1973-1975 Triumph Spitfire uses the 1895 bulb, a miniature wedge type in the T5 form factor rated at 12V and 0.9W. Its very low wattage reflects its role as a low-intensity indicator rather than a high-output lighting source.
The 1980 Triumph Spitfire specifies the 257 bulb, which is rated at 12V and 2W and accepts either a festoon or BA9s base configuration. This is notably an instrument-grade bulb, making its application in a parking light position a distinct departure from the dual-filament 1157 used in the preceding four model years.
All three bulb types across these specifications conform to ANSI standards applicable in both the United States and Canada, indicating a shared North American fitment classification.
The 257, 1157, and 1895 are not interchangeable. Each has a different base type: BA9s or festoon for the 257, BAY15d bayonet for the 1157, and a wedge base for the 1895. Physical base incompatibility prevents cross-substitution without modification.
The wattage difference between the 1157 (21W/5W) and the 1895 (0.9W) is substantial. Substituting one for the other would produce significantly mismatched light output and could place incorrect electrical load on the circuit.