Tire PSI seemingly/consistently dropping?

[SDHacker]

Isnt Ryobi usually green?(lime ish)

Yes and blue is usually Makita, Bosch or Kobalt

 

[Rogue]

Yes and blue is usually Makita, Bosch or Kobalt

Now OP can understand the landmines of just trying to get a handheld air compressor.

 

[xponents]

Now OP can understand the landmines of just trying to get a handheld air compressor.

The fact that there are home tools ecosystems is always hilarious to me. We need the same battery for a leaf blower and a lawn mower from the same brand... and in some cases its cheaper to just get a new product that comes with a battery than the battery itself.

 

[SDHacker]

What is the best compresso? Mike

Based on a recommendation from @Bobby I bought a Gooloo off amazon

 

[Bobby]

Based on a recommendation from @Bobby I bought a Gooloo off amazon

I have the Lucid one for a possible flat but use the Gooloo to top off. I bought it based on a Project Farm review. It is very small and battery operated.

 

[Genghis]

This is normal. The tire will warm as you drive and as the air in the tire warms, the pressure will increase by about 4 PSI. You should set your pressure when your tires are cold before driving.

To clarify, that's what I was actually inferring to. Cold reading with my digital handheld, I set to 45 before I drive. Early car readings will be at 42-43 but after the time periods I described, it will read 45 which was the original external cold setting. That's why I was saying the stabilized readings are more accurate than the early read in the car (at least in SoCal weather).

 

[AirPlur]

What is the best compresso? Mike

[resists urge to make coffee joke]

I have the Lucid one for a possible flat but use the Gooloo to top off. I bought it based on a Project Farm review. It is very small and battery operated.

Sweet! Picking up on of these now for $50 on amazon black friday.

 

[borski]

As @Worldwide Beagle is fond of reminding us, TPMS are not accurate. They aren’t designed to be accurate. They are designed to detect sudden drops in pressure, to let you know you have a slow leak, a not-so-slow leak, etc.

I know this has been repeated multiple times, and has become common knowledge, but... if I may challenge this assertion for a minute... I haven't actually seen a source that shows this?

Direct TPMS sensors tend to be accurate to within 1 psi, in my experience (and my gauge agrees with that). Even the internet seems to think that it has a range of +/- 3%, which on a 42PSI tire is 1.26 PSI, which is perfectly fine.

What, pray tell, makes TPMS sensors inaccurate @Worldwide Beagle ?

 

[rhbblb1]

If tire pressure is supposed to be 49, should it be 49 when cold and about 54 when hot or 44/45 when cold and 49 when hot? Never really thought about this before.

 

[SDHacker]

If tire pressure is supposed to be 49, should it be 49 when cold and about 54 when hot or 44/45 when cold and 49 when hot? Never really thought about this before.

49 when cold

 

[Worldwide Beagle]

As @Worldwide Beagle is fond of reminding us, TPMS are not accurate. They aren’t designed to be accurate. They are designed to detect sudden drops in pressure, to let you know you have a slow leak, a not-so-slow leak, etc.

There’s no substitute for a proper pressure gauge. And with an EV especially, you should be checking your pressure every few weeks. And especially when the temperature changes rapidly, or just before a road trip. It’ll make a big difference to your efficiency on longer trips.

Actually, they are pretty "accurate" for their singular limited intended purpose: low pressure event warning device. They were never designed or intended to give accurate real time psi readings, just warn when pressure is below a preset minimum. The federal mandated specs for a tpms are very low tech and the guts of the tpms cost pennies. I still like the German ABS sensor based system: go or no go.

And you rightly opine that a TPMS shoe never substitute for a quality pressure guage and a consistent protocol for measuring.

 

[Worldwide Beagle]

I know this has been repeated multiple times, and has become common knowledge, but... if I may challenge this assertion for a minute... I haven't actually seen a source that shows this?

Direct TPMS sensors tend to be accurate to within 1 psi, in my experience (and my gauge agrees with that). Even the internet seems to think that it has a range of +/- 3%, which on a 42PSI tire is 1.26 PSI, which is perfectly fine.

What, pray tell, makes TPMS sensors inaccurate @Worldwide Beagle ?

Ask @Adnillien, he makes them. They cost pennies. And not one tire manufacturer in the world, even the cheapest Chinese, recommend relying on them. Not one. Not one car company. In other words, I have never seen a source that relies on tpms for other than it's limited singular designed intended use. Anywhere. Ever.

Also, Sorry, I can't, pray tell, tell you why kicking the tires a car in the used car lot is an inaccurate way of meeasuring. Hard to prove a negative.

 

[borski]

Ask @Adnillien, he makes them. They cost pennies. And not one tire manufacturer in the world, even the cheapest Chinese, recommend relying on them. Not one. Not one car company. In other words, I have never seen a source that relies on tpms for other than it's limited singular designed intended use. Anywhere. Ever.

Also, Sorry, I can't, pray tell, tell you why kicking the tires a car in the used car lot is an inaccurate way of meeasuring. Hard to prove a negative.

lol I wasn't trying to offend; I genuinely am curious, since every source I can find looks like It says they're very accurate. I believe you! I'm just genuinely curious why, and why it's not more talked about?

 

[Electrified]

lol I wasn't trying to offend; I genuinely am curious, since every source I can find looks like It says they're very accurate. I believe you! I'm just genuinely curious why, and why it's not more talked about?

Because for as long as I can remember the TPMS and the Milton pencil gauges I have owned/own are pretty much spot on with each other.

 

[Adnillien]

Ask @Adnillien, he makes them. They cost pennies. And not one tire manufacturer in the world, even the cheapest Chinese, recommend relying on them. Not one. Not one car company. In other words, I have never seen a source that relies on tpms for other than it's limited singular designed intended use. Anywhere. Ever.

Also, Sorry, I can't, pray tell, tell you why kicking the tires a car in the used car lot is an inaccurate way of meeasuring. Hard to prove a negative.

TPMS pressure sensors are cheap to manufacture and test costs can be equal to or more than manufacturing costs. The sensors are very temperature sensitive. The accuracy depends on what and how many temperature(s) the sensor is tested and calibrated at. A well calibrated pressure sensor is very accurate. On the other hand, if a nominal temperature model is used with test at one or two temperatures, the accuracy will not be very good. Since test is a big part of the overall cost, nobody wants to pay for additional test over temperature that would provide better accuracy.

 

[Worldwide Beagle]

lol I wasn't trying to offend; I genuinely am curious, since every source I can find looks like It says they're very accurate. I believe you! I'm just genuinely curious why, and why it's not more talked about?

But accurate when? After driving 10 minutes? No good. With the tires doing 712 revolutions per mile? No good. None are accurate, that I know of, when it counts as defined by the tire manufacturers: when the tires are dead cool and motionless and shaded. Consistency! It's the hobgoblin of all engineering. No doubt some of them are very accurate some of the time.

They may anecdotely provide a measurement that is same as the true measurement, but that does not make it an accurate instrument. Even a broken clock is spot on correct twice a day.

I think it's not talked about because peoples lives at at risk. People die from underinflated tires. How do you come up with a uniform use methodology, with the tire manufacturers blessing, for hundreds of models of TPMS, with $20 a hour techs installing them, owners bashing curbs, lucid drivers devouring car swallowing potholes with their 21" Pirellis. With devices that cost pennies with no serviceable battery.

If squeezing your iPhone let an app tell you your blood pressure, would you trust it? Over you doctor? Would you risk your life on it?

Don't apologize. I am not offended. I am glad we have TPMS on our cars. I bet the dozens of Ford Explorer owners, negligently running on 15 psi, that died from Firestone tire blowouts, wish they had them.

 

[Adnillien]

I think it's not talked about because peoples lives at at risk. People die from underinflated tires. How do you come up with a uniform use methodology, with the tire manufacturers blessing, for hundreds of models of TPMS, with $20 a hour techs installing them, owners bashing curbs, lucid drivers devouring car swallowing potholes with their 21" Pirellis. With devices that cost pennies with no serviceable battery.

The pressure sensor is filled with a gel that is exposed to the air in the tire. That gel transfers the pressure to the sensor and protects the sensor for all sorts of nasty stuff in the tire like water, latex flat fix, cleaning solvent, bead seal, grease, etc. Don't even ask what happens to the gel during a Rapid Decompression Event, aka blowout.

 

[borski]

The pressure sensor is filled with a gel that is exposed to the air in the tire. That gel transfers the pressure to the sensor and protects the sensor for all sorts of nasty stuff in the tire like water, latex flat fix, cleaning solvent, bead seal, grease, etc. Don't even ask what happens to the gel during a Rapid Decompression Event, aka blowout.

Today I learned! Thank you both for the clarification <3

 

[Genghis]

They may anecdotely provide a measurement that is same as the true measurement, but that does not make it an accurate instrument. Even a broken clock is spot on correct twice a day.

Not every broken clock...

I think we all learned a lot about TPMS today so thank you. Based on what I learned, it sounds prudent to externally measure and set your tire pressure with an accurate reader probably every 2-3 weeks or when there is a big weather temp change.

 

[joec]

The temperature thing makes sense. I was raising an eyebrow to the Californians claiming these things are accurate, where mine are often as much as 3-5 psi off. Other times within 1 psi, other times spot on. Etc.

@Worldwide Beagle hit the nail on the head: consistency is what you want from any tool. And consistent these are not.

They did do their job and throw up a warning last year when the techs at Discount Tire put on my snows and then only inflated them to 42 psi. But that’s about all I’d rely on them for during a Colorado winter.