Heavy Hauler Light Sizes

it is state regulated and therefore there is no set rule. There are minimum standards in some states that are largely ignored now since the improvement in LED technology. Because most manufactured LED lighting solutions today are designed to meet or exceed those minimums such as visible distance, flash rate, color and 360 degree visibility. Most rooftop "light-bars" available will be acceptable depending on mounting, visible from the side as well as the front.
Auxiliary or added lighting is just that, added help to attract attention to the truck to make it stand out from normal. Flashing grill lights, mirror lighting and bumper lights are a good example of this and help with close quarters traffic.
If you are going with any of these please insure that they do not interfere with or overpower your directional signal lights, or add more signal lights if you are concerned that they may be.
Many jurisdictions also regulate trailer auxiliary lighting and some include 360 degree view, height above the roadway, color and flash rate. In this area you should include load extremity lighting such as extendable or swing-out lighting for night travel. Load extremity lighting can be regulated in size and there are jurisdictions that require 4" lighting although most do not specify. There are also some that insist on red to the rear for extremity lights and some want all amber. This is not usually enforced but may be used as a "reason to stop" or a extra add-on for a ticket or inspection notation.

 

Solid answer right there hand.