TPMS Monitors

They should read individual pressure not the differences to trigger the light, for example, a new f350 i believe reccomends 65 -70 psi in front and 80 psi in rear, if they went off the difference the light would constantly be on. The threshold for the tire light should be about 10% or anything below 60 psi weather it be front or rear. That being said usually you have to run at least the lowest reccomended tire pressure for the light to stay off, so if front is 65-70 and rear is 80 you should be able to set tires all the way around for 65-70 psi. there is no set forward or rearward position for a sensor, it can be moved to any place on the car. It definately sucks on the heavier trucks especially since the factory reccomended was intended for a load (what the truck is made to do) but running that high of a pressure empty ruins the tires and wears the center. The ideal pressure for a 3/4 or 1 ton truck with no load, with 10 ply 80 psi max tires is somewhere between 60-65 psi but on the newer trucks with tpms sensors the pressure you need to maintain proper tread wear is below the threshold of the range on the sensor thus the light stays on all the time. This is based off my experience at work. Ive seen cars come in with the light on and they are all low, and ive had them come in with a low individual tire and the rest someone has maxed out. I guess this is a good example, ive had cars come in where people have been running 44 all the way around, they tell me the light has just come on and ill check the tires and find one that is at 30 or less.