Final answer:
The TPMS sensor should be mounted at a 180-degree angle from the valve stem on the side of the rim.
Step-by-step explanation:
In order to determine the angle at which the TPMS sensor should be mounted from the valve stem, we need to consider the geometry of the rim. Let's assume that the rim is circular and the valve stem is located at the top. The sensor should be mounted on the side of the rim, directly opposite the valve stem. This means that the sensor should be mounted at a 180-degree angle from the valve stem.