gas at $5/gal wont bother him at all... trucks a diesel, and takes FUEL. With a 2wd truck you can run different size tires front/rear and it wont cause any issue other than your headlights pointing at the ground
This is a good question, and you are definatly thinking on the right track. On duallies, it is not just the rubbing issue, it is also the lack of a air space for cooling as well as keeping smaller rocks/debri from getting jammed between the tires. Once the tires get too close, and you actually use your truck as a truck, IE load carry rather than just a car carrying people, you can experience unexpected tire failures. And it certainly seems from your post that you are using your truck as a truck!
Your current spacing seems too close (fingwer width?), according to your door sticker, was your truck origionaly set up to use 215R16 tires? Could it have the incorrect rims? If you can just get your fingers in, is this at the bottom where the tire bulge is at? Or higher up? If it is higher up then you definatly should NOT even use the 236R16 tires as they will rub when loaded due to a increased tire bulge and of course as you know, you are setting yourself up for failure if they are too close!
BTW - spacers between the rims are definatly a no-no. If you need more space, then proper offset rims are the only PROPER way to go on a load carring truck.
Thank you for the replies, now, where I am still lost is how much more backspacing I should get (I imagine that too much backspacing would mean my inner duals get too close to suspension components, as well as front tires being too far in creating rubbing issues as well as looking funny)
Thank you dman for confirming my suspicion that spacers are a no-no. I want to make sure that my final setup is most importantly safe, not so much for my self, but most importantly other drivers, my human occupants in the truck and 4 legged-companions in the trailer.