I fitted 18 inch wheels to my yeti and had no problems. The wheels rotate less for speed/distance which marginally reduced the speed readout compared to GPS. Since the speedo is very optimistic anyway this is not an issue. As long as the wheel / tyres are the same size and wear is reasonably balanced, there will be no issue with tyre pressure monitoring or differential locks etc. I believe both VW and Audi offer larger wheels / tyres on their equivalent models, effectively on the same chassis. I think Skoda do not offer them as fashion or 'bling' wheels do not fit with their market position for the Yeti as a utility/'Ronseal' vehicle. 17" are cheaper and do all that they require.
Use what you have.