The Chevrolet City Express brake light utilizes 3157 and 2458 bulb sizes for the specific lighting components. Data for the specified vehicle covers the period from 2015 to 2018.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Chevrolet City Express uses the 3157 bulb for brake lighting across all four model years (2015-2018), indicating a consistent fitment throughout the vehicle's production run.
The 3157 is a dual-filament T25 wedge bulb rated at 12V with a 27W/7W output, where the higher wattage filament serves the brake function and the lower wattage filament serves a secondary function such as running or turn signal operation.
As a dual-filament type, the 3157 carries ANSI standardization for the United States and Canada, meaning it conforms to a recognized industry specification rather than being proprietary to a single manufacturer.
The center high mount stop light on the City Express uses the 12961 bulb across all four model years (2015-2018), a designation that corresponds to a Philips part number rather than an ANSI standard.
The 12961 is a single-filament T10 miniature wedge bulb rated at 12V and 5W, making it significantly lower in wattage than the 3157 used in the main brake positions.
The 12961 uses a W2.1x9.5d base, which is a specific wedge-type socket configuration. This base type is not interchangeable with the T25 wedge socket used by the 3157, despite both being wedge-style bulbs.
The T10 and T25 designations refer to the bulb body width in millimeters multiplied by a factor, placing the 3157 in a physically larger form factor than the 12961. Substituting one for the other is not possible due to socket incompatibility.
Because the 3157 is dual-filament and the 12961 is single-filament, the two bulbs serve fundamentally different circuit roles and are not functionally interchangeable even if a physical adapter were used.