During the landing roll on a grass runway, the airplane decelerated quicker than the pilot expected, pulled to the right, and nosed over which resulted in a ground loop. The right lower wing and right elevator were substantially damaged during the ground loop. Postaccident examination of the airplane showed that the right main landing gear wheel inner tube and tire was likely flat prior to landing due to an undetected cut in the inner tube. The flat tire resulted in wheel pant fairing to contact the grass runway and the airplane became uncontrollable. Following the accident, the inner tube was inflated by the pilot and an audible leak was observed from the cut rubber area. The pilot reported that the tube was replaced during last the condition inspection, and it was unknown what caused the cut in the inner tube.