How accurate is the onboard TMPS PSI readout?

[Dude]

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[thomasm23]

I've filled my tires up to 33 psi several times now and when I check in the menus, they're at 31 psi.

I have 2 analog stick gauges, made by Milton, and they showed about 32 psi.

After I drive for a while, the tires will go to 33 or 34 psi but this got me thinking one of them may be off a couple of pounds.

I don't have a digital gauge but I do have access to a compressor that has a digital gauge and auto shut off. I'll try that out next week. It's been hot in Texas so I've had to check either early or late in the day.

“Analog stick gauges” are notoriously inaccurate. Just invest in a small digital gauge.

I use my digital gauge in the morning when there in no direct sun on the tires. I am usually right on between my gauge and the readout on the dash.

 

[RSH]

TPMS sensors are generally accurate within 1 pound.

Ford recommends setting initial tire pressure using a gage.
Finding an accurate tire pressure guage is more challenging as people don't necessarily want to spend the money for a good one.

On the other hand, most people don't check their tire pressure anyway unless they notice a problem.

 

[Mark S.]

On the other hand, most people don't check their tire pressure anyway unless they notice a problem.

Which is why manufacturers added TPMS to their vehicles.

 

[Colonel Angus]

A thing of beauty. Perfection. Nice

 

[Blooey]

Checked when i got home from the dealer and my tires were inflated to 42 psi at the time of delivery. I broke out the tire gauge, adjusted pressures to the numbers on the door and all the fancy electronics (in car and app) tie out with my pressure gauge.... Well, as close as i can tell with the analog, dial-type gauge. They seem to be holding pretty well too.

Agreed. I have a Joe's Racing dial gauge that's pretty accurate and it matches the TPMS. Also, like yours, both our Bronco's were way overinflated when we took delivery.

 

[Dude]

A thing of beauty. Perfection. Nice

It’s very rare… others might want to take a pic and tape it over their instrument cluster

 

[CaptainNedVT]

As the weather gets cooler, it's a good idea to check your tire pressure frequently since tire pressure drops significantly as the thermometer does the same.

Rule of thumb is you lose 1 PSI for every 10 degrees F colder.

 

[Dude]

Rule of thumb is you lose 1 PSI for every 10 degrees F colder.

That’s a good rule of thumb.. last week morning temps were mid 90s and 35psi for the BS tires, a week later and temp in garage today is 79°. On the “warmer” side of garage both tires read 34psi and the opposite side tires read 33. Your rule is accurate. ?

 

[davidg4781]

I'll try to answer some questions...

I haven't had a tire gauge in maybe 10 years now. I've had portable ones with digital gauges included that seemed to be pretty accurate but that got lost in an accident. The replacement one I got for my birthday has a small analog gauge that goes to 120lbs I think... hardly able to be accurate.

I looked at gauges on Consumer Reports and one of their higher rated ones was one I had many years ago. I couldn't find it anywhere to purchase, started digging around on my own, and ended up with the stick one. It was about $10, so not cheap, but not really expensive. I wanted to get something to check the tires.

And I don't just go by the TPMS but I checked it one day, noticed it was off, and that's when I started getting curious which one was correct.

 

[Slingy]

The dash reading and my dial gauge match up perfectly. I would imagine that Ford would make this as accurate as possible given the fact that the Explorer/Firestone recall had a huge influence in making TPMS mandatory for all cars and light trucks after Sept 1, 2007. It would be foolish of Ford to take the accuracy of the system lightly by saying "oh that's close enough" after the hit they took on that mess.

 

[davidg4781]

The dash reading and my dial gauge match up perfectly. I would imagine that Ford would make this as accurate as possible given the fact that the Explorer/Firestone recall had a huge influence in making TPMS mandatory for all cars and light trucks after Sept 1, 2007. It would be foolish of Ford to take the accuracy of the system lightly by saying "oh that's close enough" after the hit they took on that mess.

This makes sense.

When it cools down tonight or tomorrow, I'll compare the analog ones with the digital gauge on another air compressor.

 

[Flash]

You should see what happens when you go from sea level up to 8,000 feet of elevation.

 

[Wazzat]

Sounds like you need to disable that screen on your instrument display.

If three read 33-35 PSI and one reads 18 PSI, then there’s a concern to be checked, other than that - be excellent to each other, and party on dudes! Ditto to turning the screen off!

 

[Wazzat]

I've filled my tires up to 33 psi several times now and when I check in the menus, they're at 31 psi.

I have 2 analog stick gauges, made by Milton, and they showed about 32 psi.

After I drive for a while, the tires will go to 33 or 34 psi but this got me thinking one of them may be off a couple of pounds.

I don't have a digital gauge but I do have access to a compressor that has a digital gauge and auto shut off. I'll try that out next week. It's been hot in Texas so I've had to check either early or late in the day.

So how many of us have picked up a new car from the dealership (or for that matter, a used car) with the tire pressures matched to what is on the door placard? How many have checked it? I‘m the guy that puts nitrogen in my tires, and turns that tire screen on every so often. If a tire gets down to 18 PSI (or thereabouts) I will know!

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