Peterbilt 265 Back Up Light Bulb Size

The Peterbilt 265 back up light utilizes 1156 and P21W bulb sizes for the rear illumination system. Available data for the specified vehicle covers a span from 1988 through 1994.

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

Years	Bulb Size
1994	1156
1991-1993	1156
1991-1993	1156 (With 4 Round Headlamps)
1988-1990	1156
1988-1990	1156 (With 4 Rectangular Headlamps)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Peterbilt 265 uses the 1156 bulb for the back up light across all listed model years from 1988 to 1994.
The 1156 is an ANSI-standard single-filament bulb rated at 12 volts and 21 watts, recognized in both the United States and Canada.
It uses a BA15s bayonet base, which is a single-contact bayonet mount with a 15mm base width, designed for a twist-and-lock installation without a separate socket retainer.
Being a single-filament bulb, the 1156 serves one dedicated function per socket, which is consistent with its application in a back up light rather than a combined stop and tail light.
For the 1988-1990 Peterbilt 265, separate fitment entries exist for vehicles equipped with 4 rectangular headlamps, though the back up light bulb size remains 1156 in both cases.
For the 1991-1993 Peterbilt 265, separate fitment entries exist for vehicles equipped with 4 round headlamps, and the back up light bulb size is again 1156 in both configurations.
The 1994 model year carries a single back up light bulb entry with no headlamp configuration qualifier.
Because the BA15s base is a single-contact design, it is not interchangeable with the BA15d base, which carries two contacts and is found on dual-filament bulbs such as the 1157.