Compared my tire pressure sensors vs. Accu-Gage
 

Aired up the tires last night. Early this morning(50 degrees) I bled all four down to 30psi with my professional accu-gage. Drove the car for several minutes to "wake up" the tire pressure sensors. When I parked the car, the TPS DIC read 32psi on all four tires, the accu-gage read 34.5psi on all four tires. Both read equal pressure all around, but have no clue which one is accurate. I stayed with the accu-gage readings.

you have another car you can test the gage with??

No, the other car doesn't have TPS.

Personally, I'd trust the gauge...

Another gage?

Mostly, my TPMS is dead on with my tire gages.

I have the same problem with my High Tech Firestone guage..:leaving:

Just borrowed a gauge from my neighbor, tested it against the Accu-Gage, they both read very close to the same. As a result, I would assume my TPS are off a bit.

I would always trust the gauge.

You have to get the TPMS calibrated then :)

I guess in this case I would go with the gauge. You don't mention your location in your profile. The TPMS system is calibrated for sea level and that could be having an effect.

There is no way you should pick up 4 plus lbs. with just a short drive unless it done in AZ. in August. I assume the drive was under 1 mile. I fine my TPS reading to be within 1 lb of 2 digital and 1 analog guage.

Any suggestions on how that's done?

:iagree:

I'm approx. 865ft above sea level.

I drove about 5 miles. fairly hard driving once the car warmed up.

Fun with gadgets!

Now is it a gage guage or gauge ??

I have 4 different pressure...gizmos and checked them all against the DIC. Once is a accu-[insert gauge variant here]. The 4 gizmos (3 digital and 1 analog) are withing .5 psi of one another, and they found the DIC to have the same varaiance. The cheapo ones actually work if they are digital and where setup correctly. And they mostly agree with the DIC. We are close to sea level.

I use to road race and I only carried the accu thing in my tool box in the day. I checked it with the Dunop and Bridgestone guys super high buck fluid filled thingy and it was .5 PSI low compared to theirs. At that point I started carrying 2 with me to cross check them.

YMMV

I'm pretty sure your GM dealer knows how to do it, not sure if they will actually do it for you tho. The other choice is Discount Tires here in Arizona, they have a service to calibrate the TPMS. Or maybe call a few mechanic shops, since many cars have these nowadays.

Mine too.

I don't think the pressure readings of the TPMS can be "calibrated" in the sense of adjusting the pressure readings. All that can be done is to be sure each monitor is linked to the proper position on the car. The TPMS reads whatever it reads, and we are stuck with that.

You know how the old saying goes,"a man that has one watch always has the correct time,a man with two watches is never quite sure".Moral.......just use one system or the other,otherwise,you will drive yourself nuts trying to figure out which one is accurate.Both are close enough in my opinion for street usage.Keeping all four tires in equal spec is more important.I.M.O.:cheers:

:iagree:

The vote seems to be 4 to 1 in favor of the TPMS. The 4 tire pressure monitors agree. The odd man out is your handheld gage.

:iagree:

A while back I bought about six Accu-gage tire pressure gauges and compared them all to each other... and also compared them to about 4 or 5 other old gauges I had laying around. The Accu-gages were all within about 1 psi of each other, quite impressive. The other old less expensive gauges varied by +/- 5 psi... went in the trash. This doesn't mean that the one Accu-Gage you have is dead accurate though. It's quite possible that it's off by 1 or 1.5 psi.

When I set my tires cold to exactly 30 psi with any one of my Accu-gage pressure gauges, the DIC will read within 1 psi on all tires, usually dead on. (I'm pretty much at sea level.)

You can't make any determinations with just one gauge... unless it's known to be calibrated to perfection.

:iagree:

I compared my Accu-gage with another hand held gage, and they both read very close. So, it could be my TPS?

The vote is now 4 to 2.

I live a mile high in Denver, Co. and my tpms always has read 2 to 3 psi less compared to my accu-gage. I set my tires cold based on the accu-gage at 30 psi, and have had perfect tire ware at 11,000 miles.:thumbs:

:iagree:

I agree. Something doesn't seem right if your pressures increased that much with just a short drive. I usually see about a 3 lb increase after a long drive.

:iagree:

Ah well I am not sure on this so don't quote me, just what I experienced, but... when I first got my vette it had chrome wheels. I didn't think $2000 was a bargain to make my vette slightly more shiny so I told my dealer could I have the regular wheels instead. He said sure, but it would take some time for 07 wheels to come in, so he let me drive it around a while (I bought my car just before the 08s came in). TPMS was fine. Then I got the call to return my car to swap the chromes out for 08s because they had no 07 tires coming in anymore. I said sure what the heck. So that's what I did, but the dealer said he had to calibrate the TPMS for the new tires. Which he did. Then after awhile the calibration went off, and I had to return the car for recalibration. This was btw the only technical problem I had ever experienced with my vette.

Besides that, I think for any measuring device there has to be a way to calibrate it. It just makes common sense and is a good engineering principle.