How to Determine Width of Trailer for Lighting Purposes

Updated 12/11/2012 | Published 12/10/2012

Question:

when a trailer width is masured,is it from fender to fender or the bed of the trailer also when having fender markers and wired to daytime running light,how do fender markers get wired to a vehicle with no daytime running light?

asked by: Anthony

Expert Reply:

To determine the width of your trailer for lighting purposes, the width is measured at the widest point of the trailer.

It is the responsibility of the trailer owner to determine the width of their trailer, and to ensure that it lit according to state and federal regulations. Your state police, highway patrol or department of transportation is a great resource for finding the regulations that apply in your area.

All clearance and marker lights are tied into the running light circuit of the tow vehicle. When the running lights of the vehicle are switched on, all marker and clearance lights on the trailer will illuminate. On vehicles with daytime running lights that do NOT illuminate the tail lights of the tow vehicle, the trailer running lights and marker lights will not illuminate unless the running lights of the tow vehicle are switched on.

expert reply by: Mike L