Tom, I think I can safely advise you that it's only going to get better and better! If you couldn't already tell, it's an obsession.

As for the tires, getting the air out was in order to get them to sink. They way you have them half buried, I would guess that they are not going to move. Once they are underwater, someone had wrote that certain types of algae build-ups could give off noxious gases. The holes will prevent any potential build up.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."