A groutless tile system including groutless tiles, wherein each groutless tile includes a substrate, a durable surface disposed within a groove defined by the substrate, the durable surface having bottom surface, and a first coupling member disposed on an edge of the substrate. The first coupling member comprises a first bendable portion and a groove, the groove having an upper surface and a lower surface. The bottom surface of the durable surface is substantially coplanar with a point between the upper and lower surfaces of the groove. The polymer matrix forming at least a portion of the substrate can be modified to reduce the weight of the groutless tile or the cost to manufacture the groutless tile. In some embodiments, the polymer matrix is modified through the use of gas nucleation or a blowing agent.