They have dual chambers to stabilize rolling and maintain functionality if one side gets punctured. Replace any that may have broken over the winter. It is a good idea to keep a few spares on hand to replace as needed. If you find tubes that are leaking replace them with new tubes. It is not a good idea to patch them unless you absolutely have to.
Tubes help hold the cover on the pool and can also prevent the wind from blowing the cover up.
Areas not properly covered with tubes are subject to these mishaps. Do not use furniture, flower pots, or your spouses favorite statuary in place of tubes. They may end up in the pool if the cover starts to slide and cause damage to liner and cover. Pump excess rain water off the cover a couple times diring the winter season. We carry a cover pump to make this a simple task.