Found tire partially flat after being parked overnight, ( approx 14 lbs air left in tire) drove vehicle to gas station nearby to fill with air. Filled tire with air, when removing the air chuck form valve stem the tip of the valve stem broke off ejecting the valvecore and thus the tire rapidly started loosing air. After further investigation, I found that the valve stem was not made of steel or brass but of aluminum. I had to have the whole valve component replaced at my local dealer and the tire was checked for leakage and since the valve was replaced it has maintained air. This valve unit is on a 2007 Chevrolet Equinox. I have researched this component and found that it is made by siemans-vdo a Continental Corp. I thought I would make you aware of this since I feel this could result in some serious accidents. It seems to me that these valve stems should be made of steel since they are an exterior component, subject to some abuse(ie:curbs, muddy roads, car washes etc.)

- Schroon Lake, NY, USA