You could even go with 15s. I just ordered a set of 15" alloys for my Ti since I already have a set of Blizzaks that were on the old Protege5. Definitely go with a second set of tires/wheels. Get inexpensive wheels and good snows-you'll probably save money in the long run since you won't have to pay for mounting and balancing twice a year. Plus, it would be a crime to run those beautiful 18" Ti rims in the winter!
2014 Focus ST2-9/9/13 Build Date-Performance Blue-Charcoal/Blue Recaros-Moonroof-Cobb Intake w/AIRPORTAL-Magnaflow-Breedt QuickShift Arm & Knob-QuickLifts-Garageline 20/25 Spacers-UK "Ford Power" Ignition Button-WeatherTech Visors-Rally Armors