So I finally got around to installing my TST-510 TPMS today. I've had it for about 9 months so far and just haven't gotten a "round tuit" to put the sensors on and program the system. Everything went on fine. Set the monitor as per instructions and everything seems to work..... EXCEPT.... my analog tire gauge says there is 100psi in each tire and the TPMS says 95....reading ambient temperature just fine. 95psi all around is fine for my load according to the pressure charts from Goodyear, but I'm now curious if my regular, analog gauge is right or if my digital TPMS is right. Any opinions??

I have three really nice fairly expensive air gauges, and none of them match when checking the pressure. So the answer is who knows. You would have to get a gauge that you know has been calibrated and is accurate, and compare it to that, but if good gauges don't even match where can you even find one you know is correct? Maybe NASA or JPL would have one?

Use a third gauge as a tie breaker?It's common to get different readings from different gauges, but 10# seems like more than normal. I like what you're doing: Trust but verify. Good plan!

GM I have three gauges and none of them match. Should I try a fourth?

I have one of the best tire gauges made by Milton. I also have a set up that ties two tires together as I inflate them. In other words, I inflate the two front tires at the same time so I know they are exactly the same pressure. I have tried two different TPMS systems and they both would vary by as much as 5 PSI on tires that I know are equal. I would not trust the TPMS for your tire pressure but I would get a good quality tire gauge to inflate your tires. Also remember that if you have tire valve stem extensions for the rear duals, they will not give you an accurate temperature of those tires.

rgatijnet1 wrote:I have one of the best tire gauges made by Milton. I also have a set up that ties two tires together as I inflate them. In other words, I inflate the two front tires at the same time so I know they are exactly the same pressure. I have tried two different TPMS systems and they both would vary by as much as 5 PSI on tires that I know are equal. I would not trust the TPMS for your tire pressure but I would get a good quality tire gauge to inflate your tires. Also remember that if you have tire valve stem extensions for the rear duals, they will not give you an accurate temperature of those tires.I'm thinking I'll use the TPMS as a "relative indicator" to know when something may be going wrong. I doubt I'll use it as the absolute in tire pressure or temperatures.

What's More Accurate? | Good Sam Community

GMandJM
Explorer
Sep 08, 2015
Cool. Glad it's working well for you. TPMS's don't make us bullet-proof, but we're safer traveling with one than without one, imho.
10forty2
Explorer
Sep 08, 2015
Follow-up after the first trip with the TPMS installed:

Although according to two separate gauges, one analog and one digital, all tires were inflated to 100psi cold, the TPMS showed that each was either 94, 95, or 96psi cold and it showed ambient temperatures in all tires. So, using relativity as the guide, I watched as I rode and the pressures increased equally by an average of 12-15psi. Temps shown never got above 104 degrees F according to the TPMS during this fairly short trip of around 30 miles at 65mph. Verified surface temps of the treads and sidewalls once we reached our destination with laser thermometer showing just slightly higher (on average about 5-10 degrees warmer) than the TPMS reading, although I'm fairly sure they had cooled down a bit after coming off the interstate until finally parking at our campsite for the weekend. When it was time to pack up and head home, the TPMS showed all tires back to their original starting pressures (from when we left home) and ambient temps, so I felt confident that all tires were good to go.

Overall, I like the peace of mind the TPMS gives me, knowing that there is something "watching" all of my tires for indications of failure. And hopefully I can avoid any future blowouts by heeding it's warning features. I will not use it was the absolute in actual tire pressures due to having two separate gauges (actually three if you count the one on my inflation nozzle) indicate that there was 100psi in all tires and the TPMS indicated an average of 5 psi less. It does, however, give me a relative indicator on what the tires are doing and I can set the warning indicators to match the parameters that will hopefully keep me on my toes in case something starts to go wrong.

For reference, the system I have is the TST 510rv with 6 wheel sensors installed and using the included stubby antenna.
GMandJM
Explorer
Sep 07, 2015
Wow - four gauges and none of them read close to each other?

See which tire shop in your area has a certified master gauge and have your tires checked to see which (if any) of your gauges are more/most accurate. Some gauges can be calibrated.

Or check out Hikerdog's link.
msmith1199
Explorer II
Sep 07, 2015
GMandJM wrote:
Are you using digital gauges or dial type, msmith? Even my cheap-o Slime gauge is within a couple pounds of my TPMS reading.

Btw, another good reason to get a TPMS is that it reads temp, which can alert you to issues that don't involve tire pressure.

I like the idea of a tire pressure equlization system, but haven't read up on them. I thought the were just for duallies.

One digital, one on my airhose, one dial, and a dial that came on the device that equalizes the pressure. So I actually have four, but I never really look at the one that comes on the air hose attachment.
rgatijnet1
Explorer III
Sep 05, 2015
Rwake901 wrote:
Funny...I have three digital (different brands) tire gauges and they all read the same. :)

That's unusual to buy three different tire gauges that are all bad. :B
Rwake901
Explorer
Sep 05, 2015
Funny...I have three digital (different brands) tire gauges and they all read the same. :)
pkunk
Explorer
Sep 05, 2015
I have 2 TireMinder digital pressure gauges that both read the same and the same as my TST system(+-) 1-2 psi.
Hikerdogs
Explorer
Sep 04, 2015
Here's a link to a tire pressure gauge test Motorhome Magazine did.

http://www.motorhome.com/rv-how-to/rv-tech-tips/testing-tire-gauges/

Note that while their original intent wasn't to pick a winner they did feel that the Milton S-976 was far and away the best of the bunch. It was dead on for every pressure they tested.

While they do cost a little more, they are rugged and seem to last for ever. I have a couple Milton gauges left over from my days as a garage owner. They are now 40+ years old and still accurate
10forty2
Explorer
Sep 04, 2015
I went out and bought a digital gauge at Auto Zone to double check. It's a "Slime" brand as well as the analog gauge that I already had is a "Slime." The digital gauge reads right on (within a pound on each tire) with the analog gauge, so I'm assuming that the TPMS is reading low. Digital gauge is showing 99 and 100lbs as well as the analog. The TPMS monitor is showing anywhere from 95-99lbs and the temperature is still reading ambient temps since I haven't moved the coach yet. We're heading out for the weekend in a little while, so I'll get a test of the TPMS' relative indication of temp and pressure increases.
holstein13
Explorer
Sep 04, 2015
The man with one watch always knows what time it is. The man with two watches, is never sure. ;-)

I'd say your digital sensors are correct. Sometimes they even have decimals. Can't beat that. Analog is for old-timers.

Yes, I'm joking.