I also have the TST system. My regular gauge is off by 2-3 psi so I cant say anything about the TST sensors. A good digital gauge is on my list. with that said the sensors are all reading the same numbers with no variance. Also, are you using a repeater? when I first got mnine I tried it out and didnt get to install the repeater. it would always drop a couple of rear tires. after I wired in the repeater it no longer drops any sensor, even on the toad! I would also replace the batteries. Ill be doing that next spring.