Dually rear track width?
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WIDTH REQUIREMENTS
The maximum width limit for CMVs on the NN and reasonable access routes was originally established at 102 inches, except for Hawaii where it is 2.74 m (108 inches). (See discussion of Reasonable Access on page 12.) To standardize vehicle width on an international basis, the 102-inch width limit was interpreted to mean the same as its approximate metric equivalent, 2.6 meters (102.36 inches) (Figure 1).
Federal width limits do not apply to special mobile equipment, which consists of self-propelled vehicles not designed or used primar-ily for the transportation of persons or property and only incidentally moved over the highways. Special mobile equipment includes the following, when moving under their own power: military or farm equipment; instruments of husbandry; road construction or maintenance machinery; and emergency apparatus, including police and fire emergency equipment. Federal rules do not require States to issue overwidth permits before allowing operation of special mobile equipment. However, if States wish to allow other vehicles more than 102 inches wide (i.e. non-special mobile equipment) to operate on the NN, then States must issue special overwidth permits.
\Federal Size Regulations for Commercial Motor Vehicles - FHWA







