Peterbilt 265 front side marker bulbs use 194 size while rear side marker bulbs use 1816 size. The replacement chart covers 1988 to 1994 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 Peterbilt 265 uses two distinct bulb types across its side marker positions: the 194 for front side markers and the 1816 for rear side markers, covering model years 1988-1994 in both cases.
Both the 194 and 1816 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to defined performance and dimensional standards shared across those markets.
The 194 bulb is a T10 miniature wedge type, operating at 12 volts with a power draw of 3.78 watts. The T10 designation refers to the bulb's tubular envelope width, expressed in eighths of an inch, placing it at 10/8 of an inch wide.
The 1816 bulb is a T3.25 miniature wedge type, operating at 12 volts with a power draw of 4 watts. The T3.25 designation follows the same tubular sizing convention, indicating a slightly narrower envelope than the T10.
Both bulb types use a wedge base, which is a baseless design where the glass envelope itself is pinched to form the electrical contacts, eliminating the need for a separate metal base.
Although both bulbs share the same 12-volt operating voltage, the 194 and 1816 are not interchangeable. The Peterbilt 265 front and rear side marker housings are fitted to their respective bulb types, and the differing wedge base sizes prevent cross-installation.
The 4-watt rating of the 1816 rear side marker bulb represents a marginally higher power draw than the 3.78-watt 194 used at the front, reflecting a small but defined difference in luminous output between the two positions.