DOT C2 retro reflective tape that alternates between white and red must be used to mark trailers and trucks that are over 80 inches wide and more than 10,000 pounds in weight. (Note – In the daylight, white is often a silver color). You can use a 6/6 (6′′ red and 6′′ white) or a 7/11 (7′′ white and 11′′ red) pattern. Minimum width is 2″ wide but wider tape can be used. Each side must have 50% coverage, evenly distributed. Two red and white (silver) strips must be used to identify the bottom rear of the trailer in the back, and the top corners of the trailer must be marked with an inverted L using solid white. Similar markings are required for the tractor part of the rig (cab). View the image below for guidance.

Below is a summary of the rule. The original FMCSA document can be consulted for an exact copy of the law. The FMCSA has established rules regulating the use of conspicuity (reflective tape) materials on trailers and the backs of the tractors that pull them. The regulations are in place to lessen the likelihood of auto drivers colliding with the back or sides of tractor trailers at night or in other situations where visibility is reduced or impaired. Additionally, they are implemented to lessen the frequency of drivers rear-ending tractor trailer rigs. These accidents take place in traffic, and also in situations where the trailer is parked and not attached to a truck, such as in parking lots at night.
The National Highway Traffic Safety Administration, or NHTSA, published a final rule on December 10, 1992, stipulating that all trailers produced on or after December 1, 1993, with an overall width of 80 inches or more and a gross vehicle weight rating (GVWR) of more than 10,000 pounds, with the exception of pole trailers and trailers made solely for living or office use, must have a method for increasing their visibility. Sides and in the back. The NHTSA decision requires the installation of reflex reflectors or red and white retro reflective tape. Two inch wide minimum. This tape is labeled to make it simple to identify and is frequently referred to as DOT C2 reflective tape. C2 simply means 2 inches.
Places to Receive Conspicuity Treatment
The location of the conspicuity treatments on trailers must be as is stated in the paragraphs that follow. The image above includes diagrams of conspicuity modifications applied to some popular trailer types.
Marking the Semi Trailer (towed portion of rig)
The trailer or semi-trailer must have the 2′′ DOT C2 retro reflective sheeting installed on both sides. Beginning as close to the front and back as is practical, each strip of retro reflective sheeting must be laid out as horizontally as possible. There is no requirement that the conspicuity treatment be continuous. The length of the entire strip, however, must be at least half as long as the trailer (50%), and the intervals between the segments must be spaced as evenly as possible. When measured with the trailer empty or unloaded, the centerline of each strip of retroreflective sheeting (or reflex reflector) must be within the range of 375 mm (15 inches) and 1,525 mm (60 inches) above the road surface, or as near to this range as is reasonably possible. In order to clear rivet heads or other similar impediments, retro reflective sheeting that is 50 mm (2 inches) wide may be divided into two strips that are 25 mm (1 inch) broad, the same length, and color, with a maximum distance of 25 mm separating them (1 inch).
Rear of Tractor Trailer Marking (back of towed portion of rig)
Retro reflective sheeting (or reflex reflectors) must be placed on the back of each trailer and semi-trailer. Retro reflective sheeting must be installed such that each strip is as horizontally aligned and spans the entire width of the trailer, starting and ending as close to the extreme edges as is practical. When the trailer is empty or unloaded, the measurement for the centerline of each strip of retro reflective sheeting (or each reflex reflector) should fall within the range of 375 mm (15 inches) and 1,525 mm (60 inches) above the road surface, or as near to this range as is reasonably possible. The bar that is below the door in the back must also be marked in the same fashion.
Upper Rear Tractor Trailer Marking
Each trailer and semitrailer must have two pairs of retro reflective sheeting (or reflex reflectors) strips installed in an inverted L pattern on the right and left upper corners of the rear of the body, as close to the top of the trailer as is practical and as far apart as is practical. Each pair must consist of two strips that are 300 mm (12 inches) in length. If the body’s perimeter is not square or rectangular when viewed from the back, the conspicuity treatments may be done along the perimeter, as close as is practical to the uppermost and outermost sections of the body’s rear on the left and right sides.
Truck’s Rear (motorized tractor part with cab)
For increased nighttime visibility, the NHTSA announced a final regulation on August 8, 1996, mandating that truck tractors constructed on or after July 1, 1997, be fitted with red-and-white retroreflective material, identical to that required on the rear of the trailers they tow. Reflex reflectors or retroreflective sheeting are both options for manufacturers. The requirement for retroreflective material near the top of the mudflap may be satisfied by material carried by temporary mudflap brackets that is transferable to the permanent mudflap system in the case of truck tractors delivered with a temporary mudflap arrangement rather than permanent equipment. A design resembling that found on trailers must also be used for the retroreflective material towards the top of the cab.
Steven Cole (Economics, MBA – University of West Florida , Business & Innovation – Stanford University) 25 years of experience in the reflective safety business. Specializing in vehicle accident and rear end collision reduction through increased visibility.