Have you tried all seven links here:

www.honestjohn.co.uk/news/parts-and-accessories/20.../

I can't actually tell you about smaller steel wheel clearances on the Kuga or whether steel wheels are fitted in any markets. The advantage is that they are about a third of the price of alloys and you don't have to worry about winter salt damage to them.

Apart from that, no reason not to go for the smallest size alloy available with the deepest profile winter tyres to get the same rolling circumference. And 18" winter tyres will still work.

I'm on Michelins for the winter. But Pirelli Sotto Zeros are good, and have a relatively high maximum speed rating.