Rear fog lightsThailand
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103. Rear fog lights
Rear fog lights are bright red lights at the rear of a vehicle that make it easier for following road users to see the vehicle when visibility is severely reduced. They are much brighter than normal rear position lights.
Because rear fog lights can dazzle or distract drivers behind, they should only be used in the weather conditions permitted by local traffic rules and should be switched off when visibility improves.
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What are rear fog lights used for?
Rear fog lights make a vehicle more visible from behind when fog, snow, heavy rain or other severe weather significantly reduces visibility.
Why are rear fog lights so bright?
They are designed to remain clearly visible through poor weather. Because of their high intensity, they can cause glare when visibility is normal.
Should rear fog lights be switched off when visibility improves?
Yes. They should only remain on while the conditions that justify their use continue. Exact legal requirements vary between countries.

Traffic rules
Thailand