The yeti greenline and the E have 16inch wheels as standard fit, and 16inch winters are skoda spec so perfectly safe, there is more choice of tyres in the 16inch, and the slightly narrower tyre will cut through the snow more, and allow snow chains to be fitted, on 17inch you can only fit chains to the rear, not a lot of good on a front wheel drive. But some have had 17inch winters fitted to the standard wheels but that means changing the tyres every spring and winter.
I have the Goodyear 4 seasons fitted on mine which is a good enough for my needs, but everybody has their own preference.
Edited by: wakev