In addition the rims go egg shape on you and the spokes pull out of the rims, the front fork will slowly bend as the rest of the bike pulls it down.
I have found that the air in the tire sinks to the bottom. If I leave it too long, I need to fix a half-flat.
For that I buy half tubes. However, if I check on the bike twice a day and switch it from hanging by the front wheel to hanging by the back wheel, the air flow evens out and I save myself the problem of half-flats.