To be honest, the first question should be "What winter tyres are made in my size?", and then the second question should be "What of those are in stock anywhere?".
I could only find eight tyres made in the correct size for the car we were putting them on. Dunlop SP Wintersport 3D, Continental ContiCrossContact Winter, Pirelli Scorpion Ice & Snow, Michelin Latitude Alpin, Bridgestone Blizzak LM-80, Vredestein Wintrac 4 xtreme, Yokohama W.drive V902A, Bridgestone DM V1.
And then finding stock was a nightmare, and this was back when I was looking in October!
In the end we just rung the dealer, and had them fit whatever their approved winter tyre was, as the summer tyres on it were also just whatever it came with from the factory. Turned out it was the Yokohama's they fitted, as Lexus UK had put in a massive order with Yokohama for each dealer to have stock of them in the correct size for every wheel size that Lexus's can come with. Plus the dealer are storing the summer tyres through the Winter (handy as our garage already has 12 wheels/tyres sat in it!) and will do the swap in Spring.
So far for dry/wet/cold roads I'm impressed with them. Feel better than the summer tyres that were on it IMHO (Dunlop something with only 500 miles on, as the car was only bought in November).