The Triumph Spitfire front and rear side marker bulbs utilize 257 and 1895 bulb sizes for replacement applications. The chart contains specifications covering 1976 to 1980 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Triumph Spitfire side marker positions use two distinct bulb types across the listed model years: the 257 and the 1895, both of which are ANSI-standardized bulbs recognized in the United States and Canada.
The 1895 bulb is a miniature wedge type with a T5 form factor, rated at 12 volts and 0.9 watts. Its wedge base means it requires no separate metal base or socket pins, as the glass envelope itself acts as the retention mechanism.
The 257 bulb operates at 12 volts and 2 watts, drawing notably more power than the 1895. It is available in either a festoon configuration or a BA9s bayonet base, which are physically distinct mounting styles.
For the Triumph Spitfire, the 1895 bulb applies to both front and rear side marker positions for the 1977-1979 model years, while the rear side marker for 1976 also uses the 1895.
The 1980 model year represents a change in bulb specification for both the front and rear side marker positions, with the 257 replacing the 1895 used in prior years.
Because the 257 is offered in two base configurations (festoon and BA9s), the physical socket type on the 1980 Triumph Spitfire determines which variant of the 257 is the correct fitment. The two base types are not interchangeable with each other despite sharing the same ANSI designation.
The wattage difference between the 257 (2W) and the 1895 (0.9W) means the two bulbs are not electrically equivalent, and substituting one for the other across model years would not conform to the original specification.