I'd suggest getting a set of used factory 18" wheels to use - I would imagine there's a bunch of smashed units out there... That way you'll be guaranteed that the sensors will fit in the wheels. We have seen some wheels where the sensors and bands won't fit due to the reduced drop well (the lower the better, as the sensor is more protected that way) - as well as we've seen some rims where the module cannot hear the sensors due to materials used to manufacture the wheels. Just my opinion...
Good luck!
