We have 3 sizes. The standard size 18 wheeler (80,000 gross weight)is 9,000 gallons of gas/7,600 diesel. (Diesel is a pound heavier than gas per gallon)
The medium size 22 wheeler is 11,400 gas/9,500 diesel in Michigan (100,000 pound gross weight) and 9,600 gas/8,300 diesel with a overweight permit in Indiana. Then we have the 34 wheeler which is Michigan only. 135,500 pound gross weight. It's 13,400 gallon of gas or 12,900 diesel. Here is the big truck.