Originally Posted by TuefelHunden
I agree and disagree. First, you can play your math games all you want, they usually don't come out right, or at least not good enough. Too many variables that are tough to get a good reading. That's why I don't trust the absolute numbers on the instrument panel. There are some rules of thumb that allow you judge the best traction by the amount of change in tire pressure as they heat up. They are difficult to figure when a compensation algorithm is playing with the numbers. That's the agree part. The disagree part is that they are not a silly gadget. I measure my air pressure and fill the tires "cold" before the bike moves. That way I know what my tire pressure actually is at under known conditions, not what some engineer thinks it should be. Why it is not a gadget is I watch the instrument reading for changes, usually loss of pressure. That is what keeps my ass intact.
This. ^^ TPMS is not there to tell you if your tires are inflated to the correct pressure to +/- 1 PSI. Use a good tire pressure gauge before you leave the house for that. TPMS is there so save your ass if you get a slow leak while riding. Happened to my buddy a few weeks ago -- he got a warning on the dash with the front down to 25 PSI. He had a slow leak and was able to limp home by topping up the tire a few times during the ride and keeping an eye on it with the TPMS.