[Gealii]

i second with Nemo taking soapy water and rubbing it all over the bead of the tire and the valve stem can lead to air bubbles allowing you to see where the leak is. It could be dirt in the bead, the rim being rusted on the inside edges, or its leaking through the rubber depending on the valve stem or tire.

I would especially not use fix a flat, the only time i use that junk is on my pedal bike when i get a flat cuz i plan on ditching the tube when i get back home anyway. It just gums up everywhere being a pain.

Replacing the tire at a professional shop would probably fix as the last set of tires i had put on they grinded all the rust off the inside of the rims.