These Civic Wheels are 12 STD, but come with a conversion kit pre-installed. This means that you get the faster 12 STD bearings, but can use them with an 8 STD fork that is compatible with 30mm wide wheels.
The Civic wheels are designed to handle high impacts and lateral stress. Their 88a urethane is the best of hard and soft wheels, as it won't get torn up easily and will still grip the various surfaces you ride. 30mm wide wheels offer a larger balance point for manuals, as well as more stability when riding backwards. Civic wheels also have a larger contact patch with the floor. This means that a larger portion of the wheel is in contact with the floor and provides superior grip compared to other 30mm wheels.