Idaho Code § 49-925: Lighting equipment on motor-driven cycles.

The head lamp upon every motor-driven cycle may be of the single-beam or multiple-beam type, but in either event shall comply with the requirements and limitations as follows:

(1) Every head lamp on a motor-driven cycle shall be of sufficient intensity to reveal a person or a vehicle at a distance of not less than one hundred (100) feet when the motor-driven cycle is operated at any speed less than twenty-five (25) miles per hour and at a distance of not less than two hundred (200) feet when the motor-driven cycle is operated at a speed of twenty-five (25) or more miles per hour, and at a distance of three hundred (300) feet when the motor-driven cycle is operated at a speed of thirty-five (35) miles or more per hour.

(2) In the event a motor-driven cycle is equipped with multiple-beam head lamps, the beams shall meet the minimum requirements set forth above and shall not exceed the limitations set forth in section 49-922, Idaho Code.

(3) In the event a motor-driven cycle is equipped with a single-beam lamp, the lamp shall be so aimed that when the vehicle is loaded, none of the high-intensity portion of light, at a distance of twenty-five (25) feet ahead, shall project higher than the level of the center of the lamp from which it comes.