Symbolism, Imagery, Allegory
Primo seems a bit obsessed with shoes, don't you think? He talks about them constantly, from the ceremony of the Exchange of Shoes to telling us about the bleeding sores he got on his feet from his poorly-fitting ones. He hopes to get a pair of real leather shoes once he starts working in the Laboratory; he recounts how the prisoners rushed to find appropriate footwear right before the evacuation of the camp.
Shoes, shoes, shoes. So, what's up with all these references?
First of all, there's the very real, physical importance of footwear. It might not seem like such a huge deal to us. But, if a prisoner's shoes don't fit properly, he's in danger of getting sores and possibly an infection, and is made more susceptible to the selections for being "unhealthy." Remember, there's no cure for "swollen feet" (2.59) and prisoners who can't work are exterminated. Shoes symbolize health and life.
What else might shoes mean? Think about those prisoners who look for good shoes just before they are evacuated. Why might they need good shoes? Because that's what you need for a long journey on foot: sturdy, well-fitting, warm shoes. On another level, shoes symbolize freedom, and the ability to move around and possibly escape. Shoes were confiscated by the millions when inmates first arrived in concentration camps. It was a powerful symbol that their freedom had been taken away. And for the ones taken directly to the gas chambers, it was a stark statement that those shoes would never again be needed.