The pilot made the landing using only 20 degrees of flaps. The aircraft touched down about one third of the length of the runway and he applied the brakes. Shortly thereafter, the aircraft entered a skid, which continued for the length of the pavement until the aircraft went off the departure end of the runway. A police air unit is based at the airport. According to the unit pilots, about a 4 knot tail wind existed at the time the aircraft landed. The officers said standing water was present on the runway surface due to a recent rainfall, and they examined the runway after the accident and said that skid marks with heavy rubber deposits were found on the runway for a distance of about 120 yards from the departure end. FAA inspectors examined the aircraft and reported that both main tires had evidence of extensive heat over a typical foot print area on the tire tread. The inspectors noted that portions of the tread crown were melted in a pattern similar to reverted rubber hydroplaning.