Why are you worried about refilling with nitrogen? All nitrogen is is a dry non flammable gas. In aircraft applications it's recommended to fill the tires with nitrogen (as opposed to dry air) because of the extreme temperature swings the tires go through (-60 thru 150 degrees in a matter of minutes). It provides a more stable, constant pressure.
Down here on the ground, there's nothing wrong with using compressed air. Preferably air from a compressor with a dehydrator. If not, so what, tire pressure and tire condition should be checked on a regular basis.
BTW, to truly fill a tire with nitrogen you first need to purge out all the air before filling the tire. Good luck going through that process.
Paying a dealership to air up your tires? Please
