045-II Wyo. Code R. § 1.1
(1) Title 31, Chapter 5 - Article 3 of the Wyoming Statutes establishes the speed regulations for all public roadways in Wyoming. The limits specified in this subsection or established as otherwise authorized shall be maximum lawful speeds and no person shall drive a vehicle on an unpaved roadway at a speed in excess of 55 mph.
(2) The statutes include a basic speed law [W.S. 31-5-301(a) ] prohibiting drivers from traveling at a speed greater than what is reasonable and prudent under the conditions and having regard to the actual and potential hazards that may exist, which recognizes that driving conditions and speeds may vary widely from time to time. No posted speed limit can adequately serve all driving conditions. Motorists must constantly adjust their driving behavior to fit the conditions they encounter.
(3) Any speed limit, other than a statutory speed limit that is posted on a Wyoming unpaved road, must be based on an engineering study. That study should include an analysis of free-flow traffic speeds and a general roadway safety evaluation. A Spot Speed Study is used to measure the free-flowing traffic speed characteristics at a specified location under the traffic and environmental conditions prevailing at the time of the study. The general safety evaluation should provide recommendations on roadway features which cannot be addressed by changing the speed limit.
(4) The main objectives of these standards is to establish proper study procedures for completing the engineering investigation in accordance with the statutes, to provide guidance in setting appropriate speed limits based on the study data, and to establish the documentation and notification procedures when establishing new speed limits on unpaved roads. These standards and procedures summarize the minimum requirements for setting speed limits on unpaved roads. A professional engineer can consider additional information when selecting appropriate speed limits on unpaved roads.
045-II Wyo. Code R. § 1.1