Go back to the basic equations for a voltage divider. Work out what value will give you the greatest 'useful range' which means the voltage varies as widely as possible across the 0-5V analog input limits.
Then work out what the current through the fuel gauge is - I suspect it should be kept down in the milliamp range because you really don't want a 5-watt heater inside your fuel tank. Do the calculations again with this new information.
While you're at it, consider what will happen if plus or minus 24V is applied to the input pin on your Arduino. Some idiot is going to plug this in backwards one day and you don't want to burn the Arduino. Put in some resistance after the divider to limit the fault current to 2mA, which will be safe for the Arduino. Check the current through your divider resistance is within that resistor's limits for both fault conditions.