How to Change a Flat Tire

Put the tire and new tube back on the rim by first lining up the valve stem with the hole that it will need to go through on the rim. This is the reverse of what you did in Step 4. You do this by working the first edge of the tire back onto the rim, easing the tube onto the rim at the same time. As you seat the first edge of the tire onto the rim, use your fingers to carefully guide the valve stem back into its hole. Finish putting the first edge of the tire completely on the rim.

When you reinsert the valve stem of the new tube into the rim, be sure that it comes straight out of the hole and not be angled in any direction. Any tilt in the valve stem tells you that the tube is not centered over the hole. You can correct this by sliding the tube and tire around the rim just a bit in the proper direction to correct the tilt.