Tyre Pressure Gauges

Hey, Big Sandy,

I'm gonna be a dufus and ask what you mean when you say you "checked them with the airline". I'm a stickler for measurement accuracy (comes with the territory in my profession) so would like to know the best way to check and calibrate my tire (er, tyre) gauges. Thanks!

 

I keep one of these (or similar) in my glovebox for the car and got another one from Halfords for the bike recently. The Halfords one is cheap crap and is a few psi out so has gone in the bin. All the pressure gauges I've ever had seem to vary a bit. Cross check with as many as you can and don't rely on garage forecourt ones either, they're all over the place.

https://www.pcl-online.com/tyre-safety-pack-tsp1t15

 

hen I was younger man, the hammer was my most useful tool. I have since grown more tolerant!

 

I have been pumping air into my tyres using a double cylinder foot pump from Aldi, the dial guage shows 34psi in the front
My pencil guage shows 32psi
I recently put new batteries in my AA branded digital guage and it showed 28psi
I increased the pressure to 34psi front and 42psi rear as per AA digital and the ride this morning is much more controlled being less heavy in the bends and feeling more confident
How do I get these things calibrated so I know for sure which it's correct

I am happier with my bike at the correct/higher pressure. Just need to watch the tyre wear a d ensure it is even

 

When I was a blacksmith...a hammer was my most useful tool.
Still like a nice shoe turning hammer.
Cheers,Ken.

 

pressure gauges are notoriously inaccurate typically +/- 4% of the gauge range, so on a gauge that registers 150 psig its +/- 6 psi. on a gauge that registers 50 psi its +/- 2 psi. Good gauges are +/- 2.5% but also is subject to the gauge range. Moral of the story buy the gauge that has the smallest range that you need a precise reading on.

 

Yes as OPP said.....
Measuring devices such as pressure gauges or flowmeters usually state their accuracy as a % FS (of Full Scale) therefore buying the lowest range possible for the task should have the smallest inbuilt error.

Obviously quality, and inevitably cost factor in here as well. I personally favour the PCL stuff but they dont come cheap.

 

thanks Eldon your explanation was easier to understand.

 

how do you know the gauge your using is accurate how do you test them its alright saying I checked it with another gauge how do you know the gauge your checking it against is accurate.

 

My minor area of my PhD in Educational Psychology was Measurement and Methodology. This discussion is a great classic example of reliability vs validity. Realiabilty being "is the measurement consistent over time"? If I use the same tire guage over time and get the same reading for the same air pressure, it's reliable. Validity is "is what I'm measuring what I think it is? Or," is my tire pressure reading of 40 psi REALLY 40 psi and compared to what gold standard?"

So, if I know my gauge is reliable but off by 4 psi, I can use that gauge (reliably!) but would need to add or subtract 4 psi to know what the validity (accuracy) is.

The $100K question if--who has the "gold standard" for tire gauges!?

 

Throw out all of the ones made in China. Your correct tire pressure can only be felt by you, and once you dial it in +/- a couple of psi the gauge should not be charged.

 

Yep, Phred. I agree about knowing your gauge and continuing to use that one. I'm not sure whether my gauge matches the gold standard for validity (whatever and wherever that may exist!) but now that I know my own gauge and tires, I'm primarily concerned about its reliability over its validity. My gauge is valid for my bikes and me.

 

Yeah easy if both agree, but how many devices do you check if you keep getting discrepancies

I use a Michelin branded digital air compressor for my bike and car tyres. My car has tyre pressure monitoring and displays the pressure of each tyre, which matches the values that the compressor shows. So either the compressor is accurate, or both car and compressor are equally inaccurate

 

Whoo-eee! This is a total feckin' can of worms. Maybe we resort to Standard Error of Measurement. Plus or minus a couple of pounds. Oooh, that just goes against my OCD grain.

 

One could also ask how the bike/tyre manufacturers actually reach a decision on what is suitable for each bike. It is certainly not an exact science and is often determined by feedback from test riders under test conditions. Put different sized riders onboard on different types of road surfaces and I should imagine that there are a considerable number of variances. It has always seemed incredulous to me that a CB500 that I once owned which was in time replaced with a Kwak GTR 1400 both ran 36 psi in the front and 42 in the rear as do a great number of different machines even though the weight and dynamics of each machine are different.

 

AAAACK!! Too many variables, too many variables!

 

Thanks for the report on this gauge, Big Sandy. I've just put one of these in my Amazon shopping cart. Sounds like it may be both reliable AND valid--valid relative to your other two gauges at least. Convergence of data, anyway. And the price is certainly right!!