It's not just a question of grip
Of course, grip is essential. And grip conditions are much more precarious when the ground is wet and cold than when the weather is warm and dry. For cars, fitting appropriate tyres with good grip on snowy or icy roads can ensure a safe and smooth ride.
But on a motorcycle, it's not just a question of grip. The other parameter that comes into play is balance. When you only have two wheels to rely on, you can lose this essential balance at any time on a snowy or icy road. Even more so if the grip, compromised by the cold, has diminished.
Tyre temperature
It is important to understand that every tyre has an ideal operating temperature. Ideal in the sense that at this temperature the tyre will perform at its best. To reach this temperature, the tyre must travel a certain number of kilometres, which varies according to the type of tyre. But in a winter context where the rubber stiffens with the cold and therefore becomes less effective in terms of grip, it is difficult, if not impossible, to reach and maintain this ideal temperature.
In competition, tyre warmers are used to warm up the tyres before the start of the race so that they are already at their ideal temperature at the start. Then, the temperature of the tyres does not drop because of the speed at which they are driven during the race.
But even if this equipment were available for use off the track, your tyres, once heated, would quickly lose their temperature in the cold as they would not be put under the same driving and speed constraints as they usually are.