Are there any tire gauge that beams a sound wave and detect the bouncing wave characters of the tire to measure the pressure? From physics point of view, it should work somehow. Anything available on market? I am tired of checking the tire pressure, especially remove and install the cap during winter time.
Haven't you seen Demolition Man where a character, I think Simon Phoenix, says "auto inflate" when he gets a flat tire? SCH-I535
It's technically possible too. Imagine a built in compressed air container in ring shape, mount inside tire, and remotely controlled on MFD based on preset pressure. A small battery can drive a needle valve to release air. The only problem I can think of, is when the compressed air half used, the whole wheel may off balance. I had this problem when I overfilled tire sealer, causing the tire off balance above 60mph.
Reminds of me trying to build a really accurate gas gauge system. Anybody who can build one to 1% will have the world beating a path to their door. In any case: problem is in the variation of the stiffness of the sidewall material. Yeah, that varies with air pressure - but it would likely also vary based upon the amount of tread left on the outside surface of the tire, and, of course, with different manufacturers. Now, if one had some kind of membrane that could freely vibrate mounted inside the tire that reacted to sound waves and would vibrate back and forth... But then one is talking about something like TPMS, and TPMS is probably simpler. Sorry 'bout that. KBeck
There is something called ultrasonic leak detection...not for tires as far as I know If you don't feel like checking figure 1 psia loss every 2 months and 1 psia loss every drop of 10 deg F ambient temp
Wikipedia said: In the United States, as of 2008 and the European Union, as of November 1, 2012, all new passenger car models (M1) released must be equipped with a TPMS. I never heard that ALL 2008 Prius has TPMS. I have a 2010 Prius, never found that feature on it.
You can get a complete TPMS that shows realtime pressure on all four corners for under $150 now: Koolertron TPMS Tire Pressure Monitor System with 4 Sensors Displayed on Your DVD Monitor
MULTIPASS! Love it! As to the "hoseless" filling system, I think the Prius' arch-nemesis has it: Self-Inflating Tires You can start on Page 3 to see a diagram of the system.
You've got it. Look at your dash when you turn the power on and all the icons light up. One of the icons looks like a cross-section of a tire with an exclamation point in it, on the right somewhere. I've got a 2010 and I've got it; so does my wife's 2008 Sienna minivan. There's a reset button for the TPMS under the driver's dash somewhere. When all the tires are inflated to their correct value you're supposed to hit that button, after which a 20% or so decrease in tire pressure will make the icon light up. If one of the TPMS sensors (in the tires) or the TPMS system itself (receivers located in each wheel well and the associated electronics and computer) fails, the icon lights up and blinks. Both the Prius and the Sienna have had that light come on. In the Prius's case this happened when I ran over a knurled bolt on a local road which did a puncture straight through the tread. On the Sienna it's happened twice: First on a long-distance trip when the tire on the front right picked up a cut on a sidewall somehow, second when the front left picked up a nail a couple years later. In all three cases this meant that my wife or I didn't have to recover the car from a sudden flat whilst driving along at speed which can, well, be deadly. Instead, one pulls over at the first opportunity, identifies the flat, puts on the spare, and starts looking for either a service station for the flat repair (2 X) or a tire shop for a new tire, or set thereof (1X). Some TPMS systems are reputed to display the actual tire pressure through some means. I've got a 2010 III which doesn't have that feature; I don't know if the Priuses with nav have that or not. But the idiot light version is good enough to hold off a crash and has probably saved a fair number of lives. KBeck.
