Thankfully we only have ice on the roads about once every 5-6 years here in Central Texas. Even when we do, it's usually melted by 10:00 am or so.
Answering the spirit of the question: I put the two wheelers up as soon as there's a risk of melt and freeze cycle. Above freezing by day and below at night means commute time is Maximum Danger of icy crap. Cold's easy to deal with, but lack of traction is not to be screwed about with.