Personally I'd stick with OEM sizes, no real need to change that aspect as the Zed isn't going to be great in proper snow regardless due to weight distribution. Remember you need wider tyres on the rear regardless of winter or summer compounds, so don't put 225/40 all the way round.
Many people (myself included) ran 225/40/18 and 245/40/18 all round on summer tyres with no ill effect, so I can't see you having any issues.