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Tire Pressure - car or gauge
Posted: Sun Jul 27, 2025 6:45 pm
by QillerDaemon
I need to ask. I filled up my tires yesterday at home. I have a air tank with a pressure hose that has a built-in gauge, and I also have a very good "professional" quality analog pressure gauge, not a cheapie by any means. The tires need 35 psi, the built-in gauge said 36, the analog gauge said 35. I got into the car to check the pressure as it has its own pressure gauge indicator on the dash, and it says 37. I got into the car to get some gas, the indicator within a few minutes said 38. At the station I got out and use the analog gauge, it said 36 with hot tires.
Got back home and let the car set a while, the analog gauge said 35, the car's pressure indicator was back at 37.
OK, so which of them do I believe? I know it's not really a good idea to let the pressure get much higher than indicated, but on the other hand it's not good to let the tires stay under pressure.
An actual Gauge getting her O-ring pressure checked:
Re: Tire Pressure - car or gauge
Posted: Sun Jul 27, 2025 7:34 pm
by CHEEZY17
Personally, I wouldn't worry about it.
Re: Tire Pressure - car or gauge
Posted: Sun Jul 27, 2025 7:53 pm
by Antknot
You’re dealing with four pressure sensors and the valve stems of the tires, and the other two gauges that you mentioned. You’re showing less than 2% difference. You’re not dealing with a laboratory quality equipment. At 2% variation is probably within manufacture spec for accuracy for everything
If it’s something that bothers you to distraction, you can always take them to a calibration specialist . However, once you get a price, you’ll decide that it doesn’t bother you that much.
Re: Tire Pressure - car or gauge
Posted: Sun Jul 27, 2025 8:32 pm
by Who
Are these gauges different political parties?
Re: Tire Pressure - car or gauge
Posted: Sun Jul 27, 2025 8:35 pm
by Antknot
Who wrote: ↑Sun Jul 27, 2025 8:32 pm
Are these gauges different political parties?
None of them are political. They’re helping, which is the opposite of what our current politicians are doing on whatever side.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 12:03 am
by QillerDaemon
Antknot wrote: ↑Sun Jul 27, 2025 7:53 pm
You’re dealing with four pressure sensors and the valve stems of the tires, and the other two gauges that you mentioned. You’re showing less than 2% difference. You’re not dealing with a laboratory quality equipment. At 2% variation is probably within manufacture spec for accuracy for everything
If it’s something that bothers you to distraction, you can always take them to a calibration specialist . However, once you get a price, you’ll decide that it doesn’t bother you that much.
Well, I appreciate this answer, so won't worry about so much. I drive a corporate supplied car that I get personal use on. Someone got a deep bug up their butt and wants to see that we were taking care of the cars like we should according to the corporate driver manual. One line of the monthly upkeep checklist is tire pressure, it should be as closely as possible to either what's on the tire or on the sticker at the driver door. I'm in IT, but some of the drivers in other departments have complained about the inspectors being real dicks about this and other things on the list. Since I don't know if the inspector if going to use the pressure indicator on the dash, or use an analog or digital pressure reader, I'm not sure what to expect, exactly.
There's also echoes of my dad in an absolute frothy lather about finding the tires on the car a few pounds too high or low. If too low "goddamit son, you waste gas with low pressure!", and if too high "goddamit son, you'll make the tires explode if they get too hot!"
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 12:55 am
by Antknot
QillerDaemon wrote: ↑Mon Jul 28, 2025 12:03 am
Antknot wrote: ↑Sun Jul 27, 2025 7:53 pm
You’re dealing with four pressure sensors and the valve stems of the tires, and the other two gauges that you mentioned. You’re showing less than 2% difference. You’re not dealing with a laboratory quality equipment. At 2% variation is probably within manufacture spec for accuracy for everything
If it’s something that bothers you to distraction, you can always take them to a calibration specialist . However, once you get a price, you’ll decide that it doesn’t bother you that much.
Well, I appreciate this answer, so won't worry about so much. I drive a corporate supplied car that I get personal use on. Someone got a deep bug up their butt and wants to see that we were taking care of the cars like we should according to the corporate driver manual. One line of the monthly upkeep checklist is tire pressure, it should be as closely as possible to either what's on the tire or on the sticker at the driver door. I'm in IT, but some of the drivers in other departments have complained about the inspectors being real dicks about this and other things on the list. Since I don't know if the inspector if going to use the pressure indicator on the dash, or use an analog or digital pressure reader, I'm not sure what to expect, exactly.
There's also echoes of my dad in an absolute frothy lather about finding the tires on the car a few pounds too high or low. If too low "goddamit son, you waste gas with low pressure!", and if too high "goddamit son, you'll make the tires explode if they get too hot!"
How often are you required to check? I can see a weekly duty cycle for vehicles assigned to an employee. If pulling from a pool for one time use then the fleet manager should do it.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 2:08 am
by CHEEZY17
If an inspector tried to give me a hard time about 36 instead of 35 I would tell him to fuck right off and laugh.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 3:52 pm
by QillerDaemon
CHEEZY17 wrote: ↑Mon Jul 28, 2025 2:08 am
If an inspector tried to give me a hard time about 36 instead of 35 I would tell him to fuck right off and laugh.
Well, when the inspector has the ability to take your keys and/or deny any personal use, you don't get to act so tough. Sayin', is all.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 4:37 pm
by Antknot
QillerDaemon wrote: ↑Mon Jul 28, 2025 3:52 pm
CHEEZY17 wrote: ↑Mon Jul 28, 2025 2:08 am
If an inspector tried to give me a hard time about 36 instead of 35 I would tell him to fuck right off and laugh.
Well, when the inspector has the ability to take your keys and/or deny any personal use, you don't get to act so tough. Sayin', is all.
Sounds like the inspectors are weak people with too much power.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 5:05 pm
by Animal
if you are getting within 2 psi readings from a few sources at different times, then that is about as good as you will ever get. I would think that a typical tire gauge would have an accuracy of around +/= 2 psi. Think of it as the standard deviation.
Re: Tire Pressure - car or gauge
Posted: Mon Jul 28, 2025 7:45 pm
by nerd_alert
Was always a fan of Gauge getting her O-ring pressure tested.
Re: Tire Pressure - car or gauge
Posted: Tue Jul 29, 2025 3:11 pm
by QillerDaemon
Antknot wrote: ↑Mon Jul 28, 2025 4:37 pm
Sounds like the inspectors are weak people with too much power.
I won't argue with that, but there they are and I have to deal with them.