Nankang AS1 235/50R18In order to get the better drainage efficiency, two straight broad grooves are applied on the outside. To enhance the safety on the wet ground, the stream in the middle groove is used to accumulate the water with the assistance of fine sipe bar to divert the water for a safer drive. Features: In order to get better drainage efficiency, two straight broad grooves are applied on the outside. To enhance safety on the wet ground, the stream in the middle