That's the story of big-box bikes. Sometimes the components are spec'ed without checking to see if they'll actually fit or work on the frame they're attached to. I've struggled with them. First, buy some new pads. These look rock hard and probably wouldn't stop a roller skate. Second, see if the caliper is centered. By that I mean, when you squeeze the lever, the pads should hit the rim at the same time. Sometimes a pad falls short because the one on the other side drops long, and centering can even them out. Third, square the pads. This one isn't parallel to the arc of the rim. Fix that. It will put more pad in contact with the rim and less in contact with the sidewall of the tire. Last, if both pads still fall short, remove them and enlarge with a rat-tail file the bottom of the loops that they bolt in to. But not too thin, you don't want them to break.