I have a 2013 Focus Titanium and for my winter tires I downsized from the 17" wheels that came with the car to 15" wheels after confirming with the dealership that the 15" wheels would fit. It is a very tight fit, but they fit with no rubbing at all.
But, even with 15" wheels and Michelin X-ice Xi3s I wouldn't say the focus is a good snow car. We just got our first big snow this weekend and I was still slipping and sliding. Probably not as bad as if I had the OEM all seasons on but still not great.
Then you're doing something wrong. I've been out in this snow all yesterday and today and have zero issues. It drives just fine.
Its hard to find 235/45R 15-16 Inch tires - would I be looking to reduce with width and ratio of the tire in this scenario? Sorry might seem a very basic question - I have no experience working with tires what so ever.
You want to keep the overall diameter of the tire the same as your current tires. You can go narrower, don't go wider. In fact, you'll likely have to go narrower anyways, depending on how wide the wheels are that you get.
For instance, my 17" tires are 215/50/17. My 15" snow tires are 195/65/15. So they are narrower, and the sidewall is much taller so they are almost the same height as my summer tires.
That's what you need to do.
For example, a good tire size for your vehicle with 16" wheels would be 195/60/16. You can deviate from that slightly, but if you're ordering new tires there is no reason to do otherwise (your speedo will be off if you do). If you get 17" wheels most your snow tire options will be "high performance" snow tires, which offer a bit less grip in deep snow and ice, but perform better on dry pavement.
