Small Potatoes, Harvest That Is

The plants that were dying back from lack of water have completely died now so I dug up one of the tires to see if any potatoes formed before the plants shriveled completely.
I had planted Yukon Gold variety and usually they do quite well in my tires instead of hills. I was surprised that we did get a few good sized ones, but the harvest is only about half of what I usually get out of a mound.