Tools and Materials Needed:

• New valve stem

• Valve stem tool (or pliers)

• Tire removal tools (optional if you're removing the tire)

• Lubricant (soapy water)

• Tire pressure gauge

• Air compressor

Step-by-Step Guide:

1. Remove the Tire from the Vehicle
   Use a jack to lift the car and remove the lug nuts with a wrench. Then, take the tire off the wheel hub.

2. Deflate the Tire
   Use a valve core removal tool to unscrew and remove the valve core from the valve stem. This will release all the air from the tire.

3. Break the Bead of the Tire (if necessary)
   If you're replacing the valve stem without removing the entire tire, you can use a bead breaker tool to separate the tire's edge (bead) from the rim. This gives you enough space to work around the valve stem.

4. Remove the Old Valve Stem
   Use pliers or a valve stem puller to grip the base of the valve stem inside the tire, then pull it out through the hole in the rim.

5. Install the New Valve Stem
   Lubricate the new valve stem with soapy water or a lubricant. Insert it into the valve hole in the rim, and pull it through using a valve stem installation tool or pliers until it is securely seated in place.

6. Reinflate the Tire
   Reinsert the valve core into the new valve stem and use an air compressor to inflate the tire to the recommended pressure. Check the tire pressure using a gauge.

7. Reinstall the Tire
   Once the tire is inflated and the valve stem is secure, mount the tire back onto the wheel hub, tighten the lug nuts, and lower the vehicle.

By following these steps, you can successfully replace a tire valve stem. Make sure the tire is properly seated and check for any air leaks around the valve stem before driving.