How to Fill a Portable Air Tank Set the portable air tank on the ground in close proximity to the air compressor. Start the air compressor. Fill the air tank to approximately 50 PSI. Continue to fill the air tank from the compressor. Click to see full answer. Beside this, how do you refill an air compressor? Steps Take your air tank to an air compressor. Attach the air hose to the tank’s fitting. Activate the air compressor to pump air into the tank. Fill the tank until the pressure is between 85 and 125 psi. Detach the air hose when the tank is filled. how many tires can a portable air tank fill? It will help, but (assuming) four tires at 50 psi from 30 psi will need more than an 11 gal tank at 125 psi. However, fill them up as you can, that will give you enough to drive to a place with air to complete the process. One may also ask, can you fill a compressed air tank at a gas station? For example, if you need compressed air in any remote location where there’s no electricity to run a compressor, you can fill up an air tank at home (or at a gas station or hardware store on your way out) and carry it into the field.Can I add another tank to my air compressor?Add another air tank. When you add another air tank, when you are not using compressed air, your air compressor will run and fill both tanks – the one that came with the compressor and the one you have just added. This means that the air compressor motor will run longer before reaching cut out pressure and stopping.