According to the pilot, after the airplane landed, it veered to the left. He initiated a go-around, applied full power, but the airplane exited the left side of the runway. The airplane continued about 100 yards across the grass apron, and into deeper grass where it struck a ditch, nosed over, and came to rest inverted. A post-accident examination of the airplane revealed substantial damage to the wings, fuselage, and vertical stabilizer. Further examination revealed the left main landing gear tire had come off the tire rim during the accident sequence, but no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.