A weight (18) is set into the lower portion of an annular space (34) in a tire (16). The weight (18) may be a precast concrete member shaped to fit into and extend chordwise of the annular space (34). The weight (18) is wider than the distance between the tire sidewalls (24, 26). When inserted into the tire (16), the weight (18) pushes the sidewalls (24, 26) apart and flattens the bottom portion of the tread (32). The weight (18) at the bottom of the tire (16) and an air space (48) at the top of the tire (16) act together to hold the tire (16) in a substantially upright position. Corrodible iron inserts may be added to the tire (16).