The concept of the structure will be explained using a spherical model. Thereby it can be seen that, by cohesion of a certain number of primary particles to aggregates in a defined state of energy, spaces (structure, pores) develop, the diameter of which depend on the size of the primary particles and hence on the surface area of the silica. The model shows that a higher structure with a given silica surface area can only be obtained when it is possible to increase the energy slate of the aggregates. Additionally it will be demonstrated in a second model (＇＇press stud＇＇ model) that the silica makes spaces available for the rubber and that the polymer chains are able, at least partially to enter into these spaces (press stud). Thus a link will be created between silica and polymer which depends on the original structure of the silica. Due to the increasing application of silicas in highly filled tread compounds the silica flier has to meet specific requirements, especially with regard to improved dispersion. One possibility to im prove those properties is the modification of the macro pore size distribution. By means of a recently developed silica, the relation of the basic work to the practical application which has been presented will be demonstrated.