DT... I guess it depends on the thickness and material of the pipe walls, though if DC are putting our wireless torque sensors inside engines I'd reckon we could see our wireless pressure sensors in Well Heads etc? Min/Max is I think as far as you like (Edit: Well, wider than in tyres anyhow. "as far as you like" could possibly be too far!) If I recall it's down to the material the SAW device is mounted on? A quick call to TRT might save some time, they should be able to divulge that information I'd of thought.
How many spokes in a Tweel? How many torque sensors? (!!!?) ...And when?! ;-)