I use a CO2 tank...Its about 8" in diameter and produces much better pressure than a small compressor.
I have been using portable tanks like this one since the eighties when we were dirt bike riding. I have used both nitrogen and CO2 to air tires. Back in the early days I used a portable tank because we did not have a genset or an electric compressor.
Then when we had a big genst and electric compressor we still used a portable tank to take to the lanes to do tires with.
This one has a preset regulator set at 140 PSI meaning I can use it to air the 115PSI tires on my RV which my electric compressor would struggle to get done.
This is reliable and pretty cheap. IMO it is more reliable than a HF cheapo compressor. In the evening you can hook it up to your quarter barrel of draft beer too!
I either carry a mother tank to refill it or spare 5# tank.
When I carry them in my trailers, I use aluminum tanks.
