When must you dim your headlights for an oncoming vehicle?

Dimming your headlights for an oncoming vehicle is required when you are within 500 feet of that vehicle. This regulation is in place to prevent blinding or distracting the driver of the oncoming vehicle, as high beams can significantly impair their vision. Using low beams at this distance ensures a safer driving environment for all road users by maintaining visibility while minimizing glare for others.

Additionally, varying distances stated in other options are designed to ensure that headlights do not interfere with the visibility of other drivers too close to each other. However, the established rule emphasizes the 500-foot requirement as the standard distance for dimming your lights in order to promote safety during nighttime and low-visibility driving conditions.