Install the tube & tire: 4 Easy Steps 1. Inflate the new tube just enough to round it out and remove any wrinkles, and place it inside the tire. Stand the wheel up (rest it against your shins) with the valve hole on top and hold the tire/tube over the wheel so that the valve is on top (inset photo).
2. Place the valve partway into the hole and simultaneously push the part of the tire edge (called the "bead") that's at the valve and closest to your legs onto the rim. With both hands moving downward away from the valve, finish working the bottom tire bead (the one closest to your legs) onto the wheel all the way around. If it won't fit onto the rim, check that the valve is inside the tire, not trapped beneath the bead.
3. With one bead in place, tuck the tube fully inside the tire and on top of the rim, which will cause the other bead to rest flush against the rim. Work this bead on starting at the valve as you did with the first. You may have to push the valve into the tire to provide clearance for the bead. Once you've got it started, work your hands away from the valve pressing the bead onto the rim around the wheel.
4. With a few inches of bead left to pop onto the rim, the tire will resist. Let all the air out. Crouch and rest the wheel on your knee to have something to push against. Now, hold the bead in place with one hand and with your stronger hand, push down to roll the stubborn section onto the rim with the heel of your hand (main photo). But don't try to pop it on all at once. Install an inch at a time, moving your hand along until you've fully installed the tire. Got it? Good job!!
Make sure that your spare tube's valve is the right type for your wheel.
Tubes that are slightly narrower than the tire fit fine and are easiest to install (for example: a 700 x 20c tube in a 25c tire and a 1.5-inch tube in a 1.9-inch tire).
A trick to create slack and ease tire installation is to go around the rim squeezing the tire beads into the rim's center (the deepest portion).
If you locate the tire label at the valve, you'll have a reference point when searching the tire for what popped the tube.