They're lightweight, so they're good for building over soft compressible ground or weak soil. If you use them as backfill behind retaining walls, they reduce the pressure on the wall, so you can have a thinner, cheaper wall. They're also a good insulator, eight times better than soil. In cold climates like Maine, they limit the depth of frost penetration and reduce problems from frost heave. They can even limit heat loss from the basements of homes.
Maine has no lack of used tires.
A survey by the Scrap Tire Management Council recently concluded that Maine has more used tires per capita than any other state. With 34 old tires per person, Maine just edges out Rhode Island which has about 31. Ohio is a distant third at nine tires per person. Construction projects have begun to make a small dent in the state's tire piles. More than half a million tires were used in the Brunswick railroad bridge and under an approach road to the new Androscoggin River bridge between Topsham and Brunswick.