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


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