There will be plenty of times where you're loaded close enough to the legal weight limits that you'll have to watch how much fuel you're carrying. You'll also have to watch how much fuel you put in when you're fuelling and calculate when it will be ok for you to fuel up the next time. The weight of the fuel itself and the placement of the fuel tanks will both influence fuel management and weight distribution while hauling loads close to the legal limit.

The Weight Of Fuel

The precise weight of diesel fuel will vary based on temperature and humidity but is around 7.25-7.5 pounds per gallon. So the safest bet is to use 8 pounds per gallon as the number you'll plug into your calculations, and that's what we're going to use here.

The Weight Distribution Of Onboard Fuel

The weight of the fuel in your tanks will be distributed mostly to your steer axle, with some going onto the drive axles. The percentage of weight that goes to each set of axles will vary from truck to truck, based upon the placement of your tanks relative to your steer and drive axles.

The best way to determine what percentage of your fuel will go to each set of axles is to weigh the truck immediately before and after fueling and do a simple calculation.

Weighing The Truck To Determine Fuel Weight Distribution

In order to determine what percentage of fuel weight goes to your steer axle versus your drive axles you can simply weigh the truck, then immediately fuel up, and then immediately reweigh the truck again to see what percentage of the added weight went to the steer axle, and what percentage went to the drive axles. Here's an example of how to do the calculations:

You scale your truck before fueling and receive your scale ticket. Here are the weights:

Steer:

8,000
Drives:

13,000
Trailer:

13,000
Gross:

34,000

After adding 100 gallons of fuel, you reweigh the truck immediately, and here's your new scale ticket:

Steer:

8,700
Drives:

13,100
Trailer:

13,000
Gross:

34,800

So from looking at your scale ticket you can see from the gross weight that you've added 800 total pounds of fuel. 700 pounds went on the steers, and 100 pounds went on the drives. So to calculate the percentage of fuel weight to the steers versus the drives, the forumula is:

Take the weight added to the steer tires (700 pounds) and divide it by the total fuel weight added (800 pounds) and then multiply that times 100:

700/800 * 100 = 87.5% went to the steer tires, and 12.5% went to the drive axles (100% - 87.5% = 12.5%). Now anytime you get fuel you'll know exactly where the weight will go.

Multiple-Choice Questions:

Question #660 (1 of 7)

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What is the best way to determine what percentage of the weight of fuel will go to each set of axles?

Simply go by the number of gallons of fuel each tank holds
Weigh the truck immediately before and after fueling, and do a simple calculation
Ask another driver what their numbers are
The percentage is standardized amongst manufacturers and is the same for every truck

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The best way to determine what percentage of your fuel will go to each set of axles is to weigh the truck immediately before and after fueling, and do a simple calculation

Question #664 (2 of 7)

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You weigh the truck immediately before and after fueling. Based on the following, determine what percentage of the weight goes to each set of axles:

Before fueling:
steer: 11,100, drives: 32,600, gross: 71,400
After fueling:
steer:11,850, drives: 32,850, gross: 72,400

75% went on the steer axle
25% went on the drive axles
65% went on the steer axle
35% went on the drive axles
67% went on the steer axle
33% went on the drive axles
80% went on the steer axle
20% went on the drive axle

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To determine the percentage of fuel weight added to the steer axle, take the weight added to the steer axle, divide it by the total fuel weight added (determined by the change in the gross weight), and then multiply that times 100

To determine the percentage of fuel weight added to the steer axle, take the weight added to the steer axle (750 pounds), divide it by the total fuel weight added (1000 pounds), and then multiply that times 100

750/1000 = .75

.75 * 100 = 75% fuel weight to the steer tires

100% - 75% = 25% went on the drive axles.

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Question #665 (3 of 7)

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You weigh the truck immediately before and after fueling. Based on the following, determine what percentage of the weight goes to each set of axles:

Before fueling:
steer: 10,200, drives: 31,300, gross: 71,700
After fueling:
steer:11,000, drives: 31,500, gross: 72,700

70% went on the steer axle
30% went on the drive axles
75% went on the steer axle
25% went on the drive axles
80% went on the steer axle
20% went on the drive axles
67% went on the steer axle
33% went on the drive axles

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To determine the percentage of fuel weight added to the steer axle, take the weight added to the steer axle (800 pounds), divide it by the total fuel weight added (1000 pounds), and then multiply that times 100

800/1000 = .8

.8 * 100 = 80% fuel weight to the steer tires

100% - 80% = 20% went on the drive axles.

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Question #659 (4 of 7)

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What is the safe number to use in calculations for the weight of fuel?

8 pounds per gallon
10 pounds per gallon
6 pounds per gallon
7.25 pounds per gallon

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The precise weight of diesel fuel will vary based on temperature and humidity, but is generally around 7.25-7.5 pounds per gallon. So the safest bet is to use 8 pounds per gallon as the number you'll plug into your calculations, and that's what we're going to use here.

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Question #662 (5 of 7)

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What is the correct method of determining what percentage of fuel is distributed between the steer axle and the drive axles?

Weigh the truck after running 100 miles, then immediately fuel up, and then re-weigh the truck to see what percentage of the added weight went to the steer axle, and what percentage went to the drive axles.
Weigh the truck, then drive exactly 100 miles, and then re-weigh the truck to see what percentage of the added weight went to the steer axle, and what percentage went to the drive axles.
Weigh the truck immediately after fueling, then run exactly 100 miles, and then re-weigh the truck to see what percentage of the added weight came off the steer axles.
Weigh the truck, then immediately fuel up, and then immediately re-weigh the truck to see what percentage of the added weight went to the steer axle, and what percentage went to the drive axles.

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In order to accurately determine what percentage of fuel weight goes to your steer axle versus your drive axles you can simply weight the truck, then immediately fuel up, and then immediately re-weigh the truck to see what percentage of the added weight went to the steer axle, and what percentage went to the drive axles.

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Question #661 (6 of 7)

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Where will the weight of fuel be distributed?

Mostly to your steer axle, with some going onto the drive axles.
Mostly to your drive axles, with some going onto the steer axle.
Entirely on your drive axles
Entirely on your steer axle

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The weight of the fuel in your tanks will be distributed mostly to your steer axle, with some going onto the drive axles.

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Question #663 (7 of 7)

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You weigh the truck immediately before and after fueling. Based on the following, determine what percentage of the weight goes to each set of axles:

Before fueling:
steer: 11,450, drives: 33,100, gross: 76,700
After fueling:
steer:11,850, drives: 33,300, gross: 77,300

67% went on the steer axle
33% went on the drive axles
75% went on the steer axle
25% went on the drive axles
88% went on the steer axle
12% went on the drive axles
73% went on the steer axle
27% went on the drive axles

Click here to look up the answer

To determine the percentage of fuel weight added to the steer axle, take the weight added to the steer axle (400 pounds), divide it by the total fuel weight added (600 pounds), and then multiply that times 100

400/600 = .67

.67 * 100 = 67% fuel weight to the steer tires

100% - 67% = 33% went on the drive axles.

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