1. Deflate the tire. Use a valve stem core removal tool to remove the core and let the air out of the tire.
2. Break the bead. Use a pair of tire irons to break the bead of the tire from the rim. This will allow you to lift the tire up and off of the rim just enough to get to the valve stem. Take special care not to pinch the inner tube against the rim of the tire when levering the sidewall over the rim of the wheel.
3. Unscrew the old valve stem. Use a valve stem wrench to loosen and unscrew the old valve stem from the inner tube.
4. Install the new valve stem. Apply a small amount of sealant to the threads of the new valve stem. This will help to seal the stem and prevent leaks. Screw the new valve stem into the inner tube until it is snug.
5. Reinflate the tire. Reinsert the valve core using the stem core tool and the replace the valve cap. Reinflate the tire to the recommended pressure and and remount the tire if it was completely removed
That's it! You have now successfully changed a valve stem without removing the tire.
