How much are 1950's Ford truck hubcaps worth?

Whatever someone will pay. If someone wants them really bad to complete a restoration they will pay plenty. This is assuming they are in Excellent condition. Put them on Ebay and see what they will bring. Take plenty of detailed clear photos and describe any defects. Or you can take them to a Auto Show and sell them. The value is dependent on the condition, rarity, and demand for the hubcaps.