ray91 replied:

I have used them before, they swell up, expand a lot left in the sun and you have to remove the caps to let the pressure out several times a day otherwise they burst (Rheem black ones). Ray

ray91 replied:

yes the steel cans dont blow up like ballons.

ROX replied:

Are we talking fuel or water or both?

bruce.h replied:

Gday Moggs
probably not a good idea to carry such heavey items on your roof as it increases your centre of gravity making your 4x4 less stable to drive, better off puting in a second tank if you can fit it,also if it is plastic i would check on the legality of carring fuel in plastic containers
Regards Bruce

felix replied:

i used to carry leaded fuel in black plastic jerry can and, yes,it did expand but i found that filling it up to its recommended level meant it never burst. in fact i have never had one burst but maybe i was just lucky.

Member - Keith replied:

Mate, Consider 10ltr stored upright (I use the Rheems) rather than the 20ltr stored on their side. Reason: lower profile, no worries about leaking caps and easier to handle. Because my truck is on LPG, I need the extra unleaded fuel for some trips. I carry these (5x10ltr) on the roof rack in a specially constructed metal tray...never, never in the cabin! Sure the centre of gravity is affected, but I always use the roof rack fuel as soon as possible on a trip. Hope this info helps. And by the way, as indicated in previous replies, the containers do expand in the heat if not full....and contract in the cold....so easy off the cap if the containers are stored empty.