Triumph Thunderbird Turn Signal Bulb Size

Triumph Thunderbird front and rear turn signal bulbs utilize 12496 and PY21W bulb sizes respectively. The replacement chart covers 2010 through 2014 model 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.

Front Turn Signal

Years	Bulb Type	Shop
2010-2014	12496	Check Price

Rear Turn Signal

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
2014	7507	PY21W	Check Price
2010-2013	12496	12496	Check Price

Bulb Specifications

Description	Type	Shop
Philips/Osram part number. Halogen bulb, specialty application. 12V.	12496	Check Price
ECE standard (Europe & worldwide). Single-filament amber bulb with BAU15s bayonet base. 12V, 21W.	PY21W	Check Price

Other Locations

Additional Notes

The 12496 is a halogen bulb operating at 12 volts, designated under Philips and Osram part numbering systems for specialty automotive applications.
The PY21W follows the ECE standard used across Europe and worldwide markets. It is a single-filament amber bulb rated at 12 volts and 21 watts, fitted with a BAU15s bayonet base.
The BAU15s base on the PY21W features offset pins, which physically prevents substitution with standard BA15s-based bulbs. This makes the PY21W non-interchangeable with many common single-filament turn signal bulbs.
On the Triumph Thunderbird, the front turn signal position uses the 12496 bulb across all model years from 2010-2014.
The rear turn signal position uses the 12496 bulb for 2010-2013, while the 2014 model year specifies the PY21W instead.
The rear turn signal fitment for the 2014 Triumph Thunderbird differs from all prior years in this specification set, requiring the PY21W rather than the 12496.