OK, story of my life here. I only know what I read. I read a lot. Unfortunately, it seems that my chickens and geese don't always read the same things I do. So it remains to be seen whether Penelope and Libby are going to find tires irresistible places to make nests. But someone on one of the BYC threads said that's what they do for their geese. The tires are on their sides, obviously, inside the shelter, One side of the tire is cut away so the goose can just walk into the inner circle of the tire (they are not particularly good hoppers or climbers). You can put lots of straw inside the tire to make a nice inviting nesting spot. And the sides of the tire keep the straw contained and the eggs can't roll away.
However, I am aware that P. and L. may turn up their adorable goosey beaks at the tires and find somewhere much less convenient (to me!!) to lay their eggs. We shall see.