I've been running for over a decade and a half and have had many running shoes from Nike and other brands. I have to put these shoes on so tight because they barely reach the heel and feel like I'm about to take them off. Literally 1/8 foot (0.125 inch or 0.317 cm) across the back would be great. They are definitely in the top 3 worst running shoes I've ever owned. I typically run 500 to 2000 miles (804 to 3218 kilometers) in my running shoes before I have to change them. If these shoes stretch at all, I don't think they'll even make it past the 500 mark.