Clearance lights

[CPittman]

What is the history of clearance lights and why do pickups have them? Why are they pretty much standard on 1-ton trucks, but not on 3/4-ton or 1/2 ton trucks? My 2500 has them and they look kinda cool, but I'm wondering why pickups have them - any clues to the past, or to the function they serve?

 

[bmoeller]

The reason the dually trucks have them as standard equipment, is because it is a gov't requirement (FMVSS 108) for vehicles over 80" or more in width.



Trucks- http://www.harristechnical.com/lamp3.htm



Trailers- http://www.harristechnical.com/lamp2.htm