A tire is filled with water by a method that includes partially filling the tire with water, introducing a water-soluble gas into the tire and venting the gas mixture to the atmosphere. The process is repeated one or more times, the amount of air in the tire being reduced on each repetition. When the amount of air remaining in the tire has been reduced to a desired level, the tire is agitated to dissolve the remaining water-soluble gas in the water. In an alternative method, air is evacuated from the tire and gaseous water is injected into the tire.