49 CFR § 393.26 - Requirements for reflectors.
(a)Mounting.Reflex reflectors shall be mounted at the locations required by § 393.11. In the case of motor vehicles so constructed that requirement for a 381 mm (15-inch) minimum height above the road surface is not practical, the reflectors shall be mounted as close as practicable to the required mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the vehicle. Temporary reflectors on projecting loads must be securely mounted to the load and are not required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on vehicles transported in driveaway-towaway operations must be firmly attached.
(b)Specifications. All required reflex reflectors (except reflex reflectors on projecting loads, vehicles transported in a driveaway-towaway operation, converter dollies and pole trailers) on vehicles manufactured on or after December 25, 1968, shall meet the applicable requirements of FMVSS No. 108 in effect on the date of manufacture of the vehicle. Reflex reflectors on projecting loads, vehicles transported in a driveaway-towaway operation, and all reflex reflectors on converter dollies and pole trailers must conform to SAE J594 - Reflex Reflectors, December 2003.
(c)Substitute material for side reflex reflectors.Reflective material conforming to ASTM D 4956-04, Standard Specification for Retroreflective Sheeting for Traffic Control, may be used in lieu of reflex reflectors if the material as used on the vehicle, meets the performance standards in either Table I of SAE J594 or Table IA of SAE J594 - Reflex Reflectors, December 2003. (See § 393.7(b) for information on the incorporation by reference and availability of these documents.)
(d)Use of additional retroreflective surfaces. Additional retroreflective surfaces may be used in conjunction with, but not in lieu of the reflex reflectors required in subpart B of part 393, and the substitute material for side reflex reflectors allowed by paragraph (c) of this section, provided:
(1) Designs do not resemble traffic control signs, lights, or devices, except that straight edge striping resembling a barricade pattern may be used.
(2) Designs do not tend to distort the length and/or width of the motor vehicle.
(5) Retroreflective license plates required by State or local authorities may be used.