Larry said: 30,000 gal seems a bit high for any state to allow. You're looking at 180,000 pounds of fuel ! Generally, 80,000 pounds gross is the highway limit. With the rig (semi tanker) at 27 to 30K that leaves you with the 7500 gal +/- capacity, depending on temp and load balance. You have to distribute the weight correctly across all axles.
Larry, When I lived in the Detroit area, over that 12 year span there were several accidents on the freeways involving the double tankers that reportedly carried 30-40k gallons of fuel. When they lit off it made a very big fire for a long time. You can see that these tankers are much larger than those used in other states, they are more of a vertical oval, like so " 0 ", using the added height to carry more. I was amazed the first time that I saw one, there are 42 tires on the ground, with only the steering axle having 2 tires, with 10 axles of 4 tires each. They look like a caterpillar worm with wheels. I've seen the same axle setup on lowboy trailers that carried steel and I saw one that had the center section of a M1-A1 tank. Even with all that support those trailers were bowed in the middle. Another innovation of such a heavy industrialized state was the longer length. There were semi trucks with 3 full sized trailers on behind them. They would only run the interstate with the long rigs. UPS was one company that used them a lot. add up these weights... the Mich statutes say: MVC 257.722 Maximum loads shall not exceed the number of pounds in the following provisions: * 18,000 pounds on an axle with at least 9 feet of spacing on each side NOTE: Weight can not exceed 700 pounds per inch of the width of the tire ("width" means as published by the manufacturer) * 13,000 pounds per axle when axle spacing is less than 9 feet between two axles but more than 3.5 feet * Axles less than 3.5 feet apart shall not exceed 9,000 pounds per axle Kevin