As you can see, probably not the best tires for snow driving with the XKR! In the video, the pavement is possibly at a 0.5-1% grade up.

PS, anyone else have that sound at around the 1:10 mark in the cold? What could it be, pulleys? The dealer wasn't able to figure it out about a year ago, and it only happens in cold weather when the engine is cold.

 

The rubber compound of summer grade tires starts to diminish when the temp dips below about 44F. At zero or sub temp, you might as well be driving on your rims. The rubber gets so hard that there is no give to the tire whatsoever. This high pitch sound that you're hearing may well be the vibration between the wheel and the tire that is otherwise absorbed by a softer rubber in normal conditions. The reason the sound eventually disappears may be due to the tires slightly warming up from driving on them, as opposed to the engine warming up.