Don-Vette

So for years I have used the gage on the left,then the other day I wanted to get a better gage,so I bought this digital one,my thinking was it must be more accurate.So when I checked my pressure the digital gage reads exactly 2 lbs. higher than my old one.So I set the pressure on my tires at 30lbs with the digital gage,and my old one reads 28lbs. Which one to believe? what are your using?

Don-Vette

It just dawned on me to check my TPM system in the DIC.I'll report back with those readings.

16Again

EDinPA

Have you changed your tires from winter air to spring air yet?

jnx911

I use one I bought from Griots. It always reads the same as my in car display. How rare is that?

FortMorganAl

I bought one of those fancy digital gauges because that seemed to be the consensus recommendation here. POS!!! It started giving totally inaccurate (low) readings after a few months. After a year it quit entirely. The old plastic case round mechanical gauge I bought in 1965 still reads within 1 pound of all 4 TPMS sensors which is as accurate as I will ever need.

People seem to forget or not realize that the TPMS system has 4 "gauges". Each tire has its own measurement sensor that is digitally reporting to the BCM with 1 pound accuracy from the sensor to the display. Any gauge that reads to 1 pound repeatability can be used to determine the accuracy of each TPMS sensor. If all 4 TMPS sensors are reading the same as the test gauge then you have 4 independent measurements telling you what the pressure is and a single hand held gauge that may or may not agree. If the hand held gauge disagrees, it is the one that is wrong. On the other hand, if the DIC says all 4 tires are at 30 and the hand held gauge says 3 are at 28 and one at 32 then you have a hand held gauge that is 2 pounds low and a single TPMS sensor that is 4 pounds low.

Don-Vette

mgtr

I think a pound or two difference in gauges is normal. I don't think it matters much (well, maybe at the track it would). I have a trucker-gauge (about a foot long, and moderately heavy) for my motorhome, and if I have questions about a gauge, I compare the accuracy to the big one.

Quick Silver Z

I use this one, easy & accurate, the bleeder is a must have...

heli-vette

I picked up this slime gauge 0 - 60 psi .
I to dislike the digital /battery junk . As for accuracy I do the Russian lab.Scientist check Compare 5 or more , against each other .. throw out the high and low . Hope your gauge is in the middle . Better to have all reading even , than actual pressure accuracy .

dvilin

I use one just like the one you have on the left. It seems to be pretty accurate and agrees with the TPM/DIC reading so all is good.

Boomer111

Not to rare because I have two different gauges that read the same as the cars readout.

wolfdogs

I use a standard cheap pencil gauge. Its accurate as anything else. I have a bunch in my storage bin and hand them out to folks on occasion too. You don't need to waste your money on these elaborate fancy do dad gauges folks..

http://www.howstuffworks.com/pressure-gauge.htm

no offense...

SilverScorp

I also have the one on the left and it is pretty accurate compared to discount tire's shop gauge reader, but it's exactly 2psi higher than the DIC numbers.

EVRose

Thats the one I have.

Quick Silver Z

I keep a pencil style in each of my vehicles for emergency use. The one I pictured above has a long enough hose to get into old eye range and you don't have to turn it around to use the pencil style's nub to bleed off your valve then push the stalk back in and recheck several times. Accurate enough to get half pound readings too (if you need that).

At 17 bucks the Vette is worth it.

gilhuly

I have a coupla pencil style gauges but none are as accurate as the one I have that looks like the one you have on the left......it agrees with my TPMS on the DIC.

RainMan12

First off, digital gauges are normally more accurate than mechanical ones for several reasons. First off, they don't have the mechanical errors that are induced from both spring type and bourdon tube type gauges. Spring type (pencil) gages are the worst. Bourdon tube are better, but they also have a mechanical gear and indicator in them, and they also suffer from parallax error. Digital gages use a pressure transducer and thus have no moving mechanical parts and the readout gives you the precise number so there is no parallax error either.

Accutire make some very good digital gages. I've tested about a dozen of them against a standard and they are all very accurate and give repeatable results. I also have a Slime brand (similar to the one pictured above) and have found the Slime unit to be off by about 1.5 psi across the board.

Another thing you should be aware of about your TPMS sensors. The chip in them not only measures psi, but it also measures the internal temperature of your tires and them employs a temperature compensation algorithm to the readout. Typically, the cold set point that TPMS sensors are calibrated to is about 68 degrees F. This means that if you set your tires to 30psi at 68 degrees F, then your TPMS numbers should track your gage measurement. The general rule of thumb is that you should add or subtract 1 psi for every 10 degrees of temp difference from your set point. So if your tires are at 78 degrees and the normal placard pressure for them is 30 psi, you should set them to 31 psi.

As your tires heat up the pressure in them increases, though you won't see it change much more than one or maybe two psi on the DIC because the TPMS sensors have already compensated for the rise in pressure due to the temp, but if you pull off and stop and check your tires when they are fully heated, you'll probably find that your gage will read several psi higher than what the DIC says.

Of course, if you are using nitrogen, this changes everything, since it doesn't expand at the same rate as normal air, because it doesn't have the moisture content in it that normal air does. So for nitrogen, you should probably set it to 30psi regardless of ambient temperature.

My personal recommendation for a good gage would be to go to Amazon.com and type in Accutire and order one of their digital gages. They have a very inexpensive ($7) key chain mode (MS-4652B) that I have tested and works well. I have about 8 of these and all 8 of them read exactly the same, and all are within half a psi of an expensive Weakon standard.

I'd stay away from the Slime gages. They don't seem to be calibrated very well.

01VETTECOP

My gauge is always 2 lbs higher than my DIC.

So I always put 32 lbs in and the DIC says 30

JoesC5

Same here. I have three pencil gauges plus a single needle air pressure gauge that is 40+ years old. I've checked all four against the DIC in my old C5 and the DIC in my C6. They all read within 1 pound of the DIC.