I remember when GrandMa refused to let Granddad in the house late at night because he was singing old folk songs and getting melancholy. Sessions at Igor's Vodka Emporium often had that effect, but this time it tipped GrandMa over the edge - in a big way. 'Go sleep with the horse, you deserve one another!' she shouted, and slammed the door in Granddad's face. He was too melancholy to react so he did what she said, and slept with the horse. Next morning he woke up out of shape - exactly - horse had slept on him for most of the night, it took two days before Granddad could stand upright again.
So, the lesson is, if you put stuff in storage, like summer tyres in winter, they may get distiorted when in storage by weight of other tyres. Also, like Granddad, tyres get old, not just by mileage. Tread might look fine, but are walls of tyres beginning to perish? So always look closely at tyres stored for winter to make sure they are fit to use.