How accurate does a tire pressure gage have to be?

[Coyote Chris]

I noted that my round , finned gages all said a tire was 30 PSI, so I decided to check all my air gages....
1. Does anyone know how to tell if a gage is accurate?
2. How accurate does a gage have to be?

 

[mikesim]

Your post reminds me of the old proverb, "A man with a watch always knows what time it is, while a man with two watches is never sure." The gold standard for TP gauges is Milton or Schrader. Buy one and use it as your standard. I use and have had very good service from a digital made by Slime. I would say that any quality gauge you buy is accurate to +- 3% plus one pound. The digital's accuracy will be on the packaging.

Mike

 

[ST1100Y]

I've this:



and this:



and in conjunction with the annually calibrated ones at the gas station:



they're all dead on...

 

[WVRider]

Like mikesim, I use the Slime digital and have found it as accurate as the Milton I've had for years, which I used when I wrenched for Honda. Its huge so I carry and use the little digital most the time.

 

[Coyote Chris]

Your post reminds me of the old proverb, "A man with a watch always knows what time it is, while a man with two watches is never sure." The gold standard for TP gauges is Milton or Schrader. Buy one and use it as your standard. I use and have had very good service from a digital made by Slime. I would say that any quality gauge you buy is accurate to +- 3% plus one pound. The digital's accuracy will be on the packaging.

Mike

So, three percent of 30 is a lb. Plus one pound. So plus or minus 2 lbs?

 

[Coyote Chris]

I've this:



and this:



and in conjunction with the annually calibrated ones at the gas station:



they're all dead on...

Your gas stations have calibrated gages?

 

[Coyote Chris]

Your post reminds me of the old proverb, "A man with a watch always knows what time it is, while a man with two watches is never sure." The gold standard for TP gauges is Milton or Schrader. Buy one and use it as your standard. I use and have had very good service from a digital made by Slime. I would say that any quality gauge you buy is accurate to +- 3% plus one pound. The digital's accuracy will be on the packaging.

Mike

Milton has three styles. A pencil, a dial and a digital.

 

[Coyote Chris]

I've this:



and this:



and in conjunction with the annually calibrated ones at the gas station:



they're all dead on...

What is the center one? FWIW,

You Absolutely Need a Tire-Pressure Gauge

Properly inflated tires last longer, are far less prone to blowouts, and make your car drive better.

www.caranddriver.com

 

[ST1100Y]

Your gas stations have calibrated gages?

Mandatory, by a shop authorized by the state's calibration office... they even have a seal on the case...
Ditto on the gas pumps... consumer protection laws...

https://www.amazon.com/Xiaomi-Compressor-Different-Inflation-Motorcycle/dp/B09JZWJ2QY

got it on sale below € 40,-, quite a nice gadget...

Upgraded it with this adapter:

https://www.amazon.de/dp/B009HP4776/?coliid=I1FGO2IC3CYJIG&colid=9MQRUK4NCGB2&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

which is really well made

 

[ARKNT]

A gauge accuracy may be tied to a % of full scale so your 100 psig gauges may be good to maybe 3psig.

Then how accurate does it need to be? To me 3-4 psi is good enough. Given the variables of road temps in the South compared to up North and things such as that it can swing real tire temps while riding quite a bit. I think consistency is as important.
I said 3-4 psi is good enough but when I set the bike's tires I set them within .5 to 1 psi as read on my gauge.

A large problem with gauges is the abuse they take getting dropped or tossed in a drawer.
I also mostly use a Slime digital. It seems consistent and trustworthy. If I was still working I might check the cal now and then but that is not convenient for me any more.

On those dial type gauges if you have a good gauge to calibrate it with you can likely reset the needle and be in working accurate order again. It looks like you may have enough gauges, just need them to work right.

Arknt

 

[mikesim]

So, three percent of 30 is a lb. Plus one pound. So plus or minus 2 lbs?

Yup!

Mike

 

[mikesim]

Really, if I were to suggest just one gauge, I would have to recommend the Slime gauge. I have had mine well over ten years (and it looks it) and it has performed faithfully every time. I keep one in each bike and car but the one that gets used more often stays in the shop. It still has the original battery!

Mike

 

[junglejim]

I have several gauges.
One for low pressure with a range of 0 - 15 PSI for my fat bike that runs about 8 PSI
Several for medium pressures about 10 - 80 for most ordinary tires
And one for high pressure truck tires that goes from 40 - 200

I think most gauges work best in the middle 2/3 of their range and less good at the extremes.
For some tires I use the gauge on the end of my thumb (think wheelbarrows and lawnmowers) And that's good enough.

 

[Coyote Chris]

A gauge accuracy may be tied to a % of full scale so your 100 psig gauges may be good to maybe 3psig.

Then how accurate does it need to be? To me 3-4 psi is good enough. Given the variables of road temps in the South compared to up North and things such as that it can swing real tire temps while riding quite a bit. I think consistency is as important.
I said 3-4 psi is good enough but when I set the bike's tires I set them within .5 to 1 psi as read on my gauge.

A large problem with gauges is the abuse they take getting dropped or tossed in a drawer.
I also mostly use a Slime digital. It seems consistent and trustworthy. If I was still working I might check the cal now and then but that is not convenient for me any more.

On those dial type gauges if you have a good gauge to calibrate it with you can likely reset the needle and be in working accurate order again. It looks like you may have enough gauges, just need them to work right.

Arknt

I think the Car and Driver folk are probably right. The gage that said 36 pounds went into the trash. Since the digital gage said 28, and two others said 28 and the whole pile of round ones said 30, I think they are all close enough. The main thing is to check them once a year....tire pressure is a moving target....relative vs absolute....and air temps and how hot the tire gets all change things....