Using the following numbers for your calculations, how much weight will come off your drive axles?
Miles per gallon: 6
Miles travelled: 360
Percentage of fuel weight on drive axles: 30%

We know that the drive axles will lose weight based on 30% of the weight of the fuel that is used when driving.
First we start by calculating the total amount of fuel that is used by dividing the total miles travelled by the miles per gallon:
Fuel used = Distance / fuel efficiency.
Fuel used = 360 miles / 6 mpg.
Fuel used = 60 gallons.
Now we can find 30% of the fuel used as a weight loss for the drive axles:
Drive axle weight loss = Fuel used * Fuel weight percentage.
Drive axle weight loss = 60 gallons * 30%.
Drive axle weight loss = 18 gallons.
Convert the weight loss from gallons to pounds: 1 gallon of diesel fuel weighs approximately 7.14 pounds.
18 gallons × 7.14 pounds/gallon = 144 pounds.