All 2008 Subaru models are equipped with direct-sensing tire pressure monitoring systems (TPMS). Each wheel contains a sensor integrated with the valve stem. If you change to aftermarket wheels, you'll need to EITHER swap your sensors over to the new wheels, or buy new sensors.

If you are SWAPPING the sensors, you'll find it's almost impossible to remove the special valve stems without tearing them. You can order just the valve stems separately.

Note that you'll need to drop by your Subaru dealership (or by Mach V Motorsports) to have the car programmed to recognize new sensors.

Includes pressure sensor and special valve stem. Some Subaru models are equiped with TPMS sensors that have metal valve stems such as the Legacy 

Note: May not work with TPMS programmers outside the U.S.