His feet!

He was jumping off a house, as usual and there was a shot where you got to see the soles of his feet. And they had all these pegs and stuff on them. Which makes sense, I guess. That Spiderman would have some sort of shoes. So I looked closer, went back and forth in the trailer... but I couldn't make out any shoes! It's just socks! Or his costume.

Does the costume have a thick sole?

I guess it doesn't really matter and it's probably a very simple answer - such as: "yes, Spiderman does in fact wear shoes". It's just that I've never thought about it before.

His feet, that is.