If you are using an LED bulb behind a red or amber lens, it's a good idea to match the color of the lens with the color of the LED bulb. If you use a white LED behind a red lens, you might end up with pink light output.
When looking at replacing your stock automotive halogen/incandescent light bulbs with a new LED product it’s important to know the differences as to how the new light bulb will act in the housing you are going to place it in.
This graphic shows how LED bulbs produce light through a red lens.
For best results, the LED color should be the same as the lens color, but if the bulb is behind a clear lens, use the appropriate color for turn and brake light functions.
As an example: a red lens will filter out all but the red portion of the light so if the light is all red, none or very little light will be blocked by the lens. The light from a white LED contains very little light in the red portion of the visible spectrum, so most of the light would be filtered out by a red lens.