I was just wondering if it would be ok to use brass fittings on an aluminum tank? Also, would I have to put some kind of sealant or teflon tape on the threads of the fittings? Thanks.
They’re pretty far apart on the galvanic scale – far enough that in highly corrosive environments one will become anodic and one will become cathodic … accelerating corrosion a la electrolysis if you just add salt water (i.e. ocean water, brine from road treatments, etc.)
Use stainless steel fittings. And yes, use thread sealant or PTFE tape for your fittings (regardless of material).
Those materials are pretty far apart on the galvanic scale – far enough that in highly corrosive environments one will become anodic and one will become cathodic … accelerating corrosion a la electrolysis if you just add salt water (i.e. ocean water, brine from road treatments, etc.) Ideally, use aluminum fittings, as even stainless steel will cause this kind of issue.
And yes, use thread sealant or PTFE tape for your fittings (regardless of material). Use either solely for a good seal but don’t expect either one to provide adequate enough separation to allow the two materials to be used together without concern for corrosion in corrosive environments.
Also, keep in mind that my answer, above, was made in the context of safety. If you live in, say, an arid desert-like region (Arizona? New Mexico? Western Texas? The Middle East?) you could probably mix the two materials and get years of good service from them. If there’s any kind of salt water that’ll contact them … I’d steer clear of mixing them.
Thanks for the detailed answer 
Well we get snow here and they do put salt stuff on the roads so my plan from the beginning was to remove my setup over the winter time. I also take my wheels off during the winter and put on some oem wheels and tires.
So provided that I did not let any salt stuff, etc get onto the brass fittings, etc. I should be ok with my plan then? I already ordered the brass fittings so thats why I am wondering lol.
If it were my setup I’d go with aluminum or stainless fittings. Aluminum’s best for obvious reasons. While stainless will still cause the same thing, it’s not as pronounced, as it’s the copper in brass that is key to the issue between aluminum and brass. (And aluminum being the nobler of the two metals is the one that will corrode first.)
300-series stainless fittings should provide the best choice for you if aluminum fittings are not an option. I didn’t mention nickel because it’s not much better than brass when it comes to mixing it with aluminum. This page contains an anodic index table that may help in your material selection: http://en.wikipedia.org/wiki/Galvanic_corrosion