A cheap way to have a red light option for one of your map lights in your car without replacing the light bulbs.
Go buy some red Tail Light Repair tape at the local Mart type store or automotive store.
I know, this is to easy, but it is much more practical than finding red replacement bulbs for your car or painting the existing bulbs.
Step 1: Remove Light Cover/lens and Add Tail Light Repair Tape to Backside
Remove light cover/lens and add tail light repair tape to backside
Step 2: Reinstall Light Cover/lens
Reinstall light cover/lens. Now you have red and white light options. FYI: When reading a civilian map with the red light, red lines or words may not show up.