THE PILOT SAID HE HAD FILLED THE LEFT FUEL TANK AND ADDED 10 GALLONS TO THE RIGHT FUEL TANK FOR A FLIGHT HE ESTIMATED TO BE ABOUT 1 HOUR AND 50 MINUTES IN DURATION. ABOUT 40 MILES FROM HIS DESTINATION THE PILOT THOUGHT THE FUEL GAGES WERE READING TOO LOW. HE DESCENDED, BANKED THE AIRPLANE TO THE LEFT IN AN ATTEMPT TO CHECK FUEL IN THE RIGHT TANK. THE ENGINE QUIT AND THE PILOT WAS TOO LOW TO RESTART THE ENGINE. HE ELECTED TO MAKE A FORCED LANDING INTO TREES. THE FAA EXAMINED THE WRECKAGE AND FOUND APPROXIMATELY 18 GALLONS OF FUEL IN THE LEFT TANK AND FOUND THE RIGHT TANK EMPTY.