I can fill these tires 3 or 4 times with a full tank.
The cost? You can get a 10# tank for less than a $150... A fill up for around 20 bucks. So with the money I save over the cost of a $600 compressor I can do 22 fill ups or 352 tires...
I like numbers, so this just caught my attention :) .
Two questions:
1) Is it 3 or 4 times? That is a 33% difference :) .
2) Do you really fill your tires up 3 times and take the near-empty tank out?
I only ask because I would be surprised if most folks go longer than two trips (1x re-inflation each, with maybe some dust-blowing and such) before refilling.
So, that $600 compared to a $150 tank* is really about 180 tires, or 45 wheeling trips, before you break even and the ARB wins the cost debate.
Three final considerations, then:
1) Isn't the Powertank like $300+? Can your average bro reliably get a functional 10lb tank setup for $150? If so, it is probably fair to also consider the occasional ARB Twins on sale for $450-500. (Also, of note, my Puma 12v is only ~90 secs slower for all 4 tires than an ARB Twin, but only costs about $250-275--the Smitty 5+ CFM compressor is in a similar arena for even cheaper).
2) Going back to the relatively extreme $600 to $150 comparison, we basically come down to folks evaluating how long they are willing to wait to make up the difference. If you wheel every weekend, and especially if you inflate other rigs' tires, even the ARB is going to pay for itself pretty quickly. If you wheel once a month by yourself (and never inflate pool toys or use air tools, it would indeed take years to make up that difference.
3) Finally, it is worth noting the convenience of having CO2 filled. I use $50/hr as my personal labor cost, and 20 minutes of my time running to the paintball or SCUBA shop nearly doubles the time-cost of a CO2 fillup. So, using the above example, I would be looking at ~25 trips--less, if I air others' tires-- before I broke even.
Just some thoughts :) .