Hi Jon, car looks great, fabulous colour!!
However, unless its a bad camera angle, It looks to me that you have C2 narrow body rear wheels fitted rather than the wide body version that your C4S should have. The rears really seem to sit a long way within the arches, particularly when viewing your 4th pic.
Have a read of the offset stamped on the wheel - C4 offset is ET 50 for Carrera Sports, which yours should be. C2 offset is ET 67, which it looks to me like these are on your car.
If you put 15mm spacers behind them, that would in effect give you the correct offset and push them out to where the C4 ET 50 offset wheel face would sit.