Fuel tank in place of my spare tire???

[LRNAD90]

Only problems are 1) as mentioned, it is only rated for water. This means the plastic compound isnt designed to stand up long term to the corrosive effects of the fuel. It would eat away at the compound, leaving particulate in your fuel and even leaking.

Possibly, thought an email to the company can probably get you specs on the material and a determination if it can 'stand up' to storing gasoline and/or diesel fuel. I suspect there is a good chance it can, and it is more legal/safety/epa issues preventing it being advertised for fuel storage, but it wouldn't be the first time my assumption was wrong.

**EDIT** - One of the vendors that sells TANK'D products states the following: "Constructed with heavy-duty linear medium density polyethylene, the tank is able to withstand road debris, automotive fluids, and chemicals."

Generally I think 'High Density Polyethylene (HDPE)' is rated for gasoline, not clear about 'Heavy Duty Linear medium density polyethylene' though. Is the vendor mistaking HDPE for MDPE ( Medium Density Polyethylene)?

2) imagine a rear end collision. Especially if the plastic was weakened due to the corrosive effect of the fuel. Likely the seams would leak before anything else. Yes, there is protection from a tow hitch installation IF you have one. I'm sure most people on this forum do, but it would be concerning to me for any debris on the road getting kicked up and gouging the unprotected tank, or if there was that rear ender.

If some expansion space is maintained, it may be safer than a metal tank (of which there are many extended range designs for many different platforms). Titan Tanks makes a 30 gallon tank that goes in place of the under bed spares of the big 3's full size trucks. It is poly as well, but only rated for diesel and they 'require' a class V tow hitch (presumably for protection). I presume the diesel only is because diesel is much less volatile in the event of a collision, but again is my assumption..

Anyway, here is a thread on IH8MUD with some 'user experiences'..

 

[LRNAD90]

Good write-up here: https://trailtacoma.com/3rd-gen/traild-spare-gas-tank-review-install-on-3rd-gen-tacoma/

Interesting, that article states you can stack 3 of the 6 gallon tanks, for 18 gallons total..

"Another cool feature? These bad boys are stackable! The super sleek design allows you to carry up to 3 of them in the spare location, which gives you an additional 18 gallons of water and/or gas storage."

**Again, note that the manufacturer does not rate tank for carrying anything other than water**

 

[Peter_n_Margaret]

I make my own plastic water and diesel tanks.
Well, I actually make the moulds from sheet metal and have a local moulder mould them for me.
The process is "rotomoulding". Powered MDPE is placed inside the mould which is then rotated through 3 dimensions inside an oven. The powdered plastic melts and deposits itself on the inside of the mould. When it has all melted the mould is cooled slowly and the plastic solidifies before the mould is opened and the part is removed.
All sorts of variations can be employed. Fancy moulds can be made from thin walled cast aluminium, threaded inserts can be moulded in, there are material choices and any colour is possible.
Canoes can be made using similar methods.
This is a great process for low volume containers. The material is inherently very tough and it can be moulded in virtually any thickness. Threaded inserts can be spin welded into the tank anywhere they are needed after moulding.
It is totally inert to the effects of fuel although gasoline (not diesel) in Australia usually requires a cross linked version (which is a bit more expensive and harder to mould) for legal reasons.
The prime issues with gasoline is the permeability of the plastic. It "seeps" through, so barrier layers are needed to reduce the minute losses.
There are no "seams" the part is made completely hollow as one piece. What look like seams are the joins in the mould, not the part.

My current vehicle has DIY rotomoulded tanks for diesel and water that are now 20 years old. They have zero additional stone protection. The pics below are new tanks for a vehicle currently under construction.
I am making tanks between 60L and 200L, typically with wall thicknesses of 6mm for water and 10mm for diesel. The vehicle will carry almost 400L each of diesel and water, all in DIY tanks.

Cheers,
Peter
OKA196 motorhome