Air Force 1 sizing guide?

Just got some AF1’s & I run a size 9.5 but these slip at the heel when I walk. Do I gotta adjust the laces or go down a size? I’ve never had this problem always get a 9.5.

Just got some AF1’s & I run a size 9.5 but these slip at the heel when I walk. Do I gotta adjust the laces or go down a size? I’ve never had this problem always get a 9.5.