C.R.S. § 42-4-1014: No commercial vehicles in the left lane - penalty.

(1) A driver of a commercial vehicle may not enter the farthest left-hand general-purpose lane when driving in the following areas of interstate 70 unless specifically required or authorized to pass by law:

(a) Between milepost 115.5 and milepost 131.0 (Glenwood canyon);

(b) Between milepost 169.5 and milepost 173.0 (Dowd junction);

(c) Between milepost 180.0 and milepost 190.5 (Vail pass);

(d) Between milepost 205.5 and 221.0 (Eisenhower-Johnson tunnel);

(e) Between milepost 224.0 and milepost 228.5 (Georgetown hill); and

(f) Between milepost 243.0 and milepost 247.0 (Floyd hill).

(2) Any person who violates subsection (1) of this section commits a class A traffic infraction.