The pilot stated during the preflight, he checked the fuel gages which indicated 12 gallons in the left wing and 18 gallons in the right wing. The right wing tank indicated just below half a tank. The pilot stated that "it is not possible to visually gauge the fuel quantity once the amount is below 30 gallons per tank," and that it is difficult to know exactly how much fuel is in the airplane. About 24 minutes after takeoff the pilot reported that the engine experienced initial indications of low fuel while operating from the left fuel tank. The pilot then switched to the right fuel tank. Instead of proceeding to his destination, 35 miles away, the pilot diverted to a closer airport, 15 miles away. After 5 minutes, the engine again demonstrated conditions consistent with low fuel. Not believing that he could make the runway, the pilot decided to make a precautionary landing in a cattle pasture about 1 mile from the airport. During the landing, the right main landing gear collapsed and the right wing was structurally damaged. Post-accident inspection of the fuel system found that both fuel tanks were nearly empty of fuel. Inspection of the right fuel gage indicated about 1/3, when in fact the fuel tank was empty.