Some cars have sensors built into the valvestem. you can tell these because it is metal with a nut on it. I worked on a ranger the other day and it is held on with pretty much a big hose clamp. The standard is for the tpms module to be located 180 degrees from the valve stem.
all i gotta say is try changing a 275/24 R22 on a harley holy shlt and they didnt tell me there was a sensor let alone it was hard enough to break the back bead and then worry about a sensor from there on in, their retarded.