From my experience in snow,
I has a Hylux on truck road tyres not good in any weather let alone -20.
Back here I used mitchelin XCL's, again not very good in anything except mud or perfect tarmac. I did run Bronco Grizzly claws in the Snow in Febuary. Now then these were actually surpringly good. Myself and another forum member linked together and towed up 2 fire engines fully fitted out when they were stuck at the botom of a hill local to us. Cannot fault the grippyness of the tyres in the snow ice. On road in the snow I was doing 45-55Mph on th icy roads no problems. Obviously you cannot brake on ice but driving around the country lanes on ice they did very well which was not expected. The best road biased tyres for snow/ice normal driving I really cannot fault were the Mitchelins that were factory on RR Classics. Cannot remember the pattern name exactly but will find out. They were superb. When they lost grip eventually everything was very controlled and secure handling wise. I did have a fling with studed Xcls these were great until the studs decided to part company with the tyres. IMO tyres are one of those great debates, almost like which LR is best. So many variables. so many different views its impossible to get a decent answer.