I know a guy that was filling in an old pond and didn't want to buy much dirt. Said he drained the pond, stacked tires in it, up to about 3' below grade then covered that with dirt. I've had others say they will eventually work their way back to surface tho, and I suspect this also violates most state's soil/water laws.
Copperheads and coral snakes love to curl up inside those old tires, especially if they have some pine needles or oak leaves fallen in them.
That rubber mulch ain't good for much--it tends to float or wash to easy. I knew a guy that tried to make a driveway out of it--no way for it to pack down and stay firm.
I also still have about 15 rolled up sections of 1/4"-3/8" rubber sheeting that used to be lining in acid tanks. About 20' x 35' each. Recycler takes those but they charge by the ton--don't remember how much now. They are heavy--had to load them with my backhoe. I'm going to take some of them, spread 'em out where I have my farm implements sitting so the grass and weeds don't grow up.
This is all stuff my father left for me to deal with..I loved him, but Dang Dad--did ya really have to accumulate all this crap?