If tyres are swapped twice a year, storage becomes more important than many people think. A tyre does not like extreme heat, strong sunlight, oil spills or being left in a damp random pile in the corner of a shed.
Before storage, it is worth washing the tyres and letting them dry. That is not just about appearance. Dirt, salt and brake dust are not things you want sitting on the tyre or wheel surface for months.
If the tyres are mounted on wheels, they can usually be stored stacked or hung, depending on the setup. If they are stored without wheels, it is generally better to keep them upright and rotate their position occasionally. That reduces the chance of deformation.
The pressure in tyres stored on wheels does not need to be at maximum, but leaving them completely flat is not a good idea either. Moderate pressure helps them keep shape. If you use storage bags, keep the tyres clean and in a dry space rather than sealed next to a hot radiator.
Avoid direct sunlight and large temperature swings. A dark, dry and relatively cool room is usually the best choice. A garage can work well as long as it is not constantly damp and full of chemical fumes.
At the end of the season, it is also smart to note which axle each tyre was on. That makes next season's installation and possible rotation easier. A small note can help you judge wear patterns much more intelligently later.
Correct storage is not complicated, but the benefit is rarely visible immediately. It is one of those maintenance habits whose value becomes clear a year or two later when the tyre set stays in better shape than one stored carelessly.