Unless posted otherwise, the maximum speed limit on the interstate is: Do you currently have car insurance? Insurance is mandatory to drive in Ohio Yes I have insurance. But please show me your best quotes. No, please help me find the best insurance. Question Unless posted otherwise, the maximum speed limit on the interstate is: Answers 55 mph. 65 mph. 70 mph. 80 mph. Explanation The maximum speed limit on interstate highways in Wyoming is either 75 or 80 mph. If a different speed limit is posted, follow the posted limit. This questions appears in the following tests: Wyoming Motorcycle Practice Test 5 Wyoming Motorcycle Practice Test 18