When to Lower Your Brights Around Semi Trucks
If you have your brights on, you must learn to dim them around vehicles - especially large semi trucks. The general rule of thumb (as seen in the image) is that you should dim your lights when you're approaching 1 block of an oncoming vehicle. It's especially important that you dim your lights at this time or sooner around semis. You see, the large side mirrors on semi trucker are especially prone to reflecting bright lights into the driver's eyes. This is so bad in some cases that it can actually create a period of blindness for the truck driver. Just to give you an idea, 2 seconds of blindness at 55 MPH is enough time for a truck to travel more than half of a football field! That's some serious distance...enough to do some real damage.
Now, I know what you're thinking, "I always dim my lights around other cars and trucks." Well, everyone thinks that, but the fact is that it's still a problem. We went to Facebook to ask some of our fans how often this happens...
"I drive team, I prefer and usually do all the night driving. But that's one of the drawbacks. Happens several times every night. Some parts of the country seem worse. For example Utah, I-70, few cars actually dim their lights. (Drunk drivers also, almost every night, at least one)" - Richard Mikulich