Story time. (In America) Headlights are supposed to angle down. There are specifics laws and in depth tests done on lights and housings to show that from about every angle they meet strict guidelines... when installed and aimed properly and in approved combination. Few states have regular lighting inspections, those that do, few inspect every car in depth. Even still, it’s easy enough to set lights up for inspection in an hour or less and return them after until next time. Very few people bother to have their headlights aimed, and many facilities or mechanics aim them wrong anyway either out of lack of skill or workmanship, or simply because most people perceive improvement in visibility when they aim their lights wrong. From inside the car the can see further down road and that helps make them feel like their mechanic returned their car in tip top better than dropped off shape. Now....
Most after market (didn’t come on the car when brand new and weren’t sold for that car by the company that made it,) light kits and conversions are not approved for compliance with lighting standards. What you get is all over the place. Thin chance it meets specs but they just didn’t bother. Usually they are designed to again- make you feel good about buying them by being as bright as possible- without caring WHERE or HOW the light is focused or bleeds out. Then are kits just “thrown together” with recycled or untested/barely tested designs and components, which may be better or worse, and the minority are approved housings and components. These of course are only approved for a specific application, and when properly installed and paired to approved components. Buy things like “projector” or “HID” or “LED” conversions are almost never approved. Often an older sealed beam housing is replaced by a non approved or approved replaceable bulb housing (like an H4 bulb conversion.) if a...
.. quality non USA approved housing or a USA approved housing are used it may not be bad at all. No promises though since if it isn’t US approved there’s no way to know unless you do the tests yourself using special optical equipment in a lab. But what happens next is usually that someone buys a cheap “HID” or “LED” universal kit (which are almost never approved for road use) and shoves it into a housing made for a halogen bulb. Halogen bulbs emit light from all sides and approved ones generally have areas of the bulb “shielded” to prevent light patterns that would blind others. Xenon (HID) bulbs generally produce light along one side that radiates out and have one side covered to prevent unwanted light. LED lights are directional- each LED produces a beam which travels straight. The reflectors required to produce a focused and controlled beam from each, as well as the systems required for things like high/low beams are very different. So the biggest issue is when people retrofit...
... non approved housings and or lighting systems, and then compound the issue by not matching the light bulb the housing is suited to with the housing. Then they usually go a step further and aim them wrong- and THEN... temperature. There are specified ranges in Kelvin for types of lights- head, tail, side marker, reverse, etc. Kelvin is the “temperature” of light color. 4500k is yellowish white like an incandescent lamp or most halogen lights. 5-6k is a white color, with more of a “blue” tint to the light as you approach and exceed 6k. Around 8-10k the “blue” starts becoming purple, and so on. an approved housing must fall within the prescribed legal ranges of color for a light type while using the specified bulb. If you test a light with a clear halogen 9004 and get approval for a red side marker, you can’t sell it with a blue LED and stamp it as approved. So many people replace bulbs with not only different types, but also different colors (Kelvin) which can further cause issues...
... THEN, there’s ride height. To be sold in the United States, there are distances a car must meet in its measurements. One dimension (that can be slightly bent with special exception by car makers if they want to spend the money to do so,) is a distance measured from the ground to the bottom of the headlight, or the ground and the bottom of the tail light. Every vehicle is supposed to have its lights fall within this range. That’s why cars and trucks originally sold as “higher” or “taller” tend to have lights mounted lower on their bodies, and “short” or “low” cars tend to mount lights high up. If you remember “pop up lights,” aka “retractable headlamps” this was a major reason for their popularity. At first technology didn’t exist for modern molded light housings. So it was often a style choice or aerodynamic choice since only a small handful of square/circle/rectangle bulbs were available. Look at old cars- they all had the same headlights, just arranged differently or styled up...
... those lights were, for a long time, the only legal lamps that could be used on a car. Pop up lights not only hid the lights for styling reasons, and helped aerodynamics, but since they “raise” above the cars bumper, they allowed the cars to be lower and more swept in front while still meeting headlight height laws. The newer molded housings on cars coupled with how cars kept getting bigger, and crash safety required higher front ends anyway, was a major contributor to the death of pop up lights and why you don’t see them after the early 90’s. The reason for the height laws are simple. Some cars are lower or higher, but headlights should not only help you see, but help others see you- brake lights obviously need to be seen even by big trucks. But those laws are also so that you don’t blind others. Properly adjusted lights at factory ride height in approved combinations don’t generally cause problems for other drivers....
... vehicles which are “lifted,” either through suspension kits, frame shims, using a wheel and tire combination with a larger outer diameter than factory specification, etc- even with headlights adjusted to factory spec will likely cause issues because the factory spec assumes factory headlamp position, not the new raised position you’ve put them in. Likewise, a lowered car might raise its headlight aim higher than factory spec to compensate for the fact the beams do not shine far enough ahead of the car to be useful once lowered. However- the closer the car is to the ground, the more moving the headlights up brings them parallel to the road, inclreasing the risk of shining the lights in other drivers eyes....
... both lifted and lowered vehicles may be outside the intended range and tested angles for factory lighting systems. Since you or your mechanic have created a new system the designers didn’t plan for, the results are only as good as your knowledge and R&D or luck. It’s geometry, but the beam won’t have the same optical properties when viewed from the intended angles since the assumption was that your car would be at a given height, and the other car would be within the factory range of headlight height- and thus the drivers vision would be within a generally predictable area. Changing the variables without adjusting accordingly is likely to cause issues. So- if we compound all these issues together as is often the case- we run into annoying and dangerous, most often illegal, and hard/not a priority to enforce lighting issues.
Assuming factory lights are kept to the factory intended specs and components and well maintained, on a “stock” car, and properly aimed- they generally shouldn’t blind. However- it is possible they still will. Especially if there is great discrepancy in height of your vehicles or effective height due to terrain differences. Older cars tended to have lower “belt lines” and sat occupants lower. Newer cars tend to move seats and bumpers higher up for safety and to better align the bumpers of cars with the common SUV so that they an perform their duty in accidents. LED lights are most likely to “blind” because of the fact that they are: directional. The light is emitted straigh out of the LED in a beam as opposed the the “halo” of other types. That means for a given glare or lumens, you’re still “seeing” more light at once because it is focused in one place. If you aren’t directly in line with the LED, it should be ok, but when you are...
.... it can suck. LED us a newer technology. As such early LED assemblies were tested on specs based on those used for approval of other types of automotive lightin for reflection, cut off, etc. the unique properties of LED lights weren’t completely considered, although they weren’t ignored. In general the intensity of LED lighting may be unpleasant or uncomfortable at times, but in most vehicles and considering all are newer and “as sold,” it tends to be very brief and intermittent based on alignment to the vehicle in question. There may be further legislation on LED lights in the future, but their benefits and the money involved as well as politics surrounding them make legislators reluctant to curtail them too severely.
In 1962 a European consortium of bulb- and headlamp-makers introduced the first halogen lamp for vehicle headlamp use, the H1. Shortly thereafter headlamps using the new light source were introduced in Europe. These were effectively prohibited in the US, where standard-size sealed beam headlamps were mandatory and intensity regulations were low. US lawmakers faced pressure to act, due both to lighting effectiveness and to vehicle aerodynamics/fuel savings.[8][9] High-beam peak intensity, capped at 140,000 candela per side of the car in Europe,[10][11] was limited in the United States to 37,500 candela on each side of the car until 1978, when the limit was raised to 75,000.[12][13] An increase in high-beam intensity to take advantage of the higher allowance could not be achieved without a move to halogen technology,[12] and so sealed-beam headlamps with internal halogen burners became available for use on 1979 models in the United States. -Wikipedia on headlights. Check your facts.
OEM headlights have a specific dispersal pattern that aftermarket lights don't have. They claim more light and such but it's basically just high beams all the time. Especially the cheaper LED's, they just put super bright lights is reflectors with no thought to the dispersion pattern. Do some research on lights before you buy them, cheaper isn't always better.
Lampposts in the UK are increasingly being replaced with LED bulbs as well, it results in patches of very bright lit up pavement then a plunge into darkness before being dazzled again.
I've been complaining about this shit for many years now; never heard anybody else so I figured my eyes were changing or something. It really is past due for some legal action; lights were just fine 15 years ago, AND more retards are driving around with their brights on and I NEVER see cops do anything about it.
I always figured there should be strict limitations on how bright standard headlights can be, but no limitations on high-beams or fog lights, as you're meant to turn those off in the presence of opposing traffic anyway.
THANK GOD it's BEEN BOTHERING ME I CANNOT SEE YOU STUPID ASS TRUCKS SOMETIMES I JUST ALLOW THEM TO GO IN FRONT OF ME AND PUT MY BRIGHTS ON SO THEY KNOW HOW IT FEELS
Your answer was way more comprehensive and complete.