They are made with Valve Stems (See Picture Below). You can get them from any Chevy Dealer or some of the Sponsors here on Camaro5 such as
www.gmpartshouse.com
patrick@gmpartshouse.com or
www.Tirerack.com
After installing them with your new Wheels, you will have to do the TPMS Reset as explained below (Copied from patrickt from GM Parts House)
PM learn procedure
Alot of times when people get these off of me they have trouble programming them. So hence I am posting this up for all to see. This will work for OEM GM sensors only! (it may work with aftermarket sensors but I do not know for sure)
Alternate DIC Relearn Enable Method
Apply park brake (manual transmission only).
Ignition ON, activate the Relearn mode with the driver information center (DIC) display controls. A double horn chirp sounds indicating the Relearn mode has been enabled and the left front turn signal will also be illuminated.
Starting with the left front tire, activate the tire pressure sensor by using one of the following methods:
Hold the antenna of the TPM tool aimed upward against the tire sidewall close to the wheel rim at the valve stem location. Press and release the activate button and wait for a horn chirp. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.
Warning: Over inflating tires may cause personal injury or damage to the tires and wheels. When increasing tire pressure do not exceed the maximum inflation pressure as noted on the tire sidewall.
Increase/decrease the tire pressure for 8-10 seconds then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the 8-10 second pressure increase/decrease time period has been reached. Once the horn chirp has sounded, the sensor information is learned and the turn signal in the next location to be learned will illuminate.
After the horn chirp has sounded and the right front turn signal is illuminated, repeat step 2 for the remaining 3 sensors in the following order:
4.1. Right front
4.2. Right rear
4.3. Left rear
When the left rear sensor has been learned and a double horn chirp has sounded, the learn process is complete and the BCM exits the Relearn mode.
Ignition OFF, adjust all tires to the recommended pressures.