I want to setup a little biodiesel operation in a shed in the back yard and start running it in my truck so I would like to put in a auxilary tank(s) in the truck to carry as much as possible on road trips. I'm a little concerened about my front axle weight, right now I've got about 3850 on the front with a 4400 max, if I put a tank at the front of the bed (say 100 gal) how much of the weight will I see on the front axle? If I run a bed tank and a under bed pass side? Thanks

 

If your aux tank is located halfway between the axles, the weight will be split 50/50.

Example: Lets say its about halfway, 100 gallons @ 8 lbs/gal + 30lb tank weight = 830 lbs; 415 lbs on each axle.

 

A few things to consider:

1. At standard temperature ,15c/59F, the density lbs/gal of 100% BioDiesel is 7.33 lbs/gal, #2 Diesel is 7.07 lbs. Therefore, depending on the % BioDiesel mix your weight can vary on 100 Gallons of fuel anywhere from 707 lbs (100% #2 Diesel) to 733 lbs (B100). Plus in winter, depending on where you live, it can weigh a bit more due to increased density.

2. Depending on the tank material (steel Vs alum), thickness and construction (internal baffles?) your AUX tank weight can vary considerably. You need to obtain actual empty tank weights from mfg's. FYI - I have a 30 Gal AUX/Toolbox and it weighs 175 lbs EMPTY and it is a combination of baffled steel tank with alum shell toolbox with transfer pump.

3. You should be able to dial in the weight transfer, fore and aft, a bit better if you know your wheelbase and the centerline location of a symmetrical tank ahead of the axle. Let's say the CL of your bed mounted AUX tank is 21" ahead of the rear axle on a Quadcab shortbed and your wheelbase is 141". Your weight transfer would be closer to a 15/85 ratio of weight transfer fore/aft.

4. Example; Lets say for nice round numbers you have a 100 Gal Aux Tank that weighs [100 lbs empty] with 100 Gal of B50 [715.50 lbs fuel] located 21" ahead of rear axle; it would add 122 lbs weight to front axle and 693 lbs weight to rear axle.

Obviously, if you add additional tanks elsewhere, underbed passenger side for instance, you are changing the weight transfer both fore and aft and side to side. It would also be interesting to scale each tire independentally with full fuel and driver on board to understand how symmetrically or asymmetrically the tires are loaded.

Anyway hope this helps a bit.

 

Cool I was thinking it would be fairly straight forward, didn't know the bio weighed a little more, Thanks!

 

I have 105 gallon steel diesel tank on my bed( i have a skirted flatbed) and it is all the way to the front against my headache rack. I see you have basically the same truck as i do, a 1 ton will not notice this little bit of extra weight. Is it a legal issue in Colorado, if not i would put against the cab and not worry about the weight. I have had them this way for years on many different trucks(all 1 tons) and have never had a problem with to much weight. These trucks will handle alot more weight than what most people think. I hope this helps you Dave