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I would like to check the air pressure in my Prius' tires. I know they should be checked when cold and I know what the pressure should be. But how do I get an accurate reading? I have one of those small pressure gauges that's about 20 years old. Another choice is to use a service station air pump but of course they can read all over the place. Or I could wait until I take it to Toyota service for maintenance but do I trust them to get it right?

Ultimately, do I need to purchase a good tire pressure gauge to get an accurate reading?
 

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I bought an Asian import digital guage at Savon Drug store (or where ever it was), a long time ago for $10. "PriusPete" checked the calibration later (don't know how) and pronounced it right on. IMHO such devices should be adequate for the task at hand.

DAS
 

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My favorite tire gauges are the dial ones. Target used to have a good one but they stopped carrying it. Extremely accurate as far as I could tell. The local auto shop should have dial ones too. They are much better than the slider ones and even though I'm a techie, I don't think I care much if my tires are 32.0 lbs or 32.2 lbs. I'd rather have good old analog with no batteries required.
 

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Pretty much *any* tire gauge, even the dirt cheap ones are plenty accurate and have incredibly good repeatability (especially considering how simple the mechanism inside is).. The biggest difference I see in a cheap gauge vs. an expensive one is the quality of materials used, especially in the sampling head (the part of the gauge you apply to the tire valve)- good ones seal perfectly every time and don't let much, if any, air escape when you apply/remove the gauge; with cheap gauges, you can lose so much air applying/removing the gauge that the reading is useless..

Now the digital ones are really not worth it IMO- when I first heard of them I thought that someone finally invented some sort of miniature direct-reading pressure transducer based on a strain gauge or a piezo element or something, but if you look up the patent number, these digital tire gauges basically use a mechanical movement that translates pressure into linear displacement, and the amount of movement is digitized and converted back into a digital pressure reading (ie, basically, they've miniaturized a regular mechanical pressure gauge and slapped a digital interface on the back end).. Additionally, the digital reading is only good to +/-1 PSI on the cheap ones, and even the most expensive model only reads to +/- 0.5 PSI, so for example, you'd only ever get 38.0 and 38.5 readings, but never 38.3.. The last strike against digital tire gauges is that the majority of them have really cr*ppy sampling heads- they leak like a sieve unless you happen to get them onto the valve stem just right..

If you're going to spend a bit more, your best bet is a good quality dial-reading gauge, but otherwise, as I said, pretty much *any* gauge is going to be good enough.
 

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:) I wanted a large analog gauge (dial). Ordered from Racer Parts Wholesale

http://www.racerpartswholesale.com

A bit more expensive, but easy to read down to the #, even ½#. Shipped cost was $30.63.

I suppose you can spend as much or little as you want. One caveat: Be sure to specify the pressure range you desire... I chose 0-60 PSI - needed the 60# range for the high-pressure spare.
 
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