During the landing approach, the pilot decided to land the tundra-tire equipped airplane on a slopped, grassy area adjacent to the taxiway due to snow on his initially intended landing area. After touchdown, the airplane began to follow the slope, and the pilot applied the uphill brake, which resulted in a ground loop. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preaccident mechanical anomalies with the airplane that would have precluded normal operation.