Make sure your tire structure has numerous holes drilled in all the tires so air and later pond gasses can escape and/or are tied down very well. I would drill at least some holes even if the tires are tied down.
I drilled holes and weighted the tires with rocks inside and still had one that floated to shore and had to re-sink.
A person wants all the voids to be filled with water, not pond gasses, so the fish and pond critters can utilize the space.
One addition to our pond I like was adding some permanent moorings for our small boat. We get lots of wind, so our pontoon paddle boat would blow around a lot when we fished from it. Tried a couple different anchors but they would hang up on my different tree stumps, concrete cribs and tree limb fish structures. Finally went scuba diving and tied off a number of mooring ropes with small floats attached to my large concrete structures. The small floats are unobtrusive yet mark some of the structures for fishing reference from the bank and now we can easily boat up to them and tie off the boat. Based on the wind direction and letting out different lengths of rope, we can position the boat on about any part of the pond we want to fish. Earth anchors in the pond bottom would work also. Just a thought.
