Headlight laws are under the DOT traffic laws and you can find them on your states Registry of Motor Vehicle website or call your local police station and they can very quickly explain the law to you.
The issue with running an HID bulb or any other high focus bulb like that in a factory halogen housing is that it does not project the same and becomes obnoxiously blinding even at low intensity. A halogen housing which your Ranger has is made to reflect light from a halogen designed bulb. An HID bulb that you find in BMW, Audi, Acura, and more have special housings that focus the light projected so that it does not reflect and scatter as it does in a halogen housing.
Because HIDs in halogen housings scatter is why it is illegal. The light is intense from every angle and becomes blinding to anyone in front of it. A projector housing focuses the light into an intense forward projection and allows an adequate amount of that light to the sides and down but not at the intensity it allows for the straight ahead projection. There is also a top cut of point in which the light can not travel upward enough as to blind someone in their rear view you are following from behind.
If you ever notive a new BMW coming toward you the headlights are very bright on angles but when the car gets straight with you and closer the light is projected correctly and it does not glare at you.
Almost all aftermarket projectors are cheap and dont focus the light properly.
Even vehicle manufacturer HID projectors dont work perfect and still blind other drivers. The point of focus in say and F250 truck is almost directly in the eye of any car driver. So while that F250 wont blind other trucks as high as it, it will blind every vehicle that sits lower.
HIDs seem to be very popular with the younger crowd customizing and being different but overall they are an obnoxious light that many drivers wish were never invented for automobile use. I myself have put the heel of my boot through numerous vehicles headlights with those bulbs at stop lights after they have been following me at night and even durring the day which is worse than at night especially in your rearview mirror.
Give it some thought. Be polite and if you really want those type lights get a projector housing and aim them low out of the eyes of other drivers. Overall if you follow the laws with changing to HIDs youll notice you actually only gain a minimal distance and actually lose light to the sides and top vs the normal halogen housings with clear lenses and Silver Star bulbs. Most aftermarket HID setups are installed in an illegal fashion not following the law guidelines and while they do project far more light its also why they blind everyone else. A proper installed and operating HID setup is not suppose to project like a spotlight and light up the roofs of 3 story homes.
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