The importance of a good tire gauge!
 

I hyperinflated without even knowing it.

Stopped at a gas station about 2 weeks ago about 1/2 mile from where I was working (so tires were almost completely cold). Their fill chuck looked like this
http://images1.hdpi.com/product/camp...feldMP5142.jpg
It's the kind where the psi slider comes out when you release the fill lever.

Oil change place had put my tires back down to 35 psi, I was going to put them back to 42 psi (44 max on sidewall). I filled one tire and double checked with my personal gauge. Mine read 42, their read 41 psi. Close enough for me.

At this point someone else came up waiting for air, so I filled the other 3 quickly just using the gauge on the pump.

Oil change place checked em today. Wow. That slider must have been sticking or something. 1 tire had 39 psi, not bad. One was 60 psi! The other 2 were in the low 50's. :eek:

Now I am paranoid and will probably carry around 5 different gauges to verify tire pressure with all of them! I just wanted to put this out as a heads up not to make the same mistake I did. My gauges correlated on the 1st tire, but I should have double checked each one. 60 freaking psi! :mad: Of course, who knows how many times that air chuck had been ran over by cars, beaten against the pavement, and whatever. I feel stupid for believing what it told me now. :(

You aren't the only one. I believe there was a thread or post by someone else before who said they inflated their tires accidentally to 60 psi or so and then had a blowout. Good thing that didn't happen to you.

My tire guage, let me show it to you. :D

I have tinted the different parts different colors. I blanked out some of the background to get the files size down.

Clockwise from the upper left:
The red thing is a male quickrelease connector for my air hose.

The blue is an adjustable air pressure regulator, adjusted for a max pressure of 15% or so LESS than the max scale on the pressure gauge, see below.

The green is a tire inflater that harbor freight had on sale for $5 or so at the springfield MA store a while back.

The yellow is a pressure guage with a maximum scale of 100 PSI.
This is not the guage that came with the inflator originally. The original gauge had a maximum scale of 250 PSI, so that the gauge needle would not peg and bend when the inflator was attached to a 249 PSI air supply by the user. :D
I had to remove the original gauge (the threads are glued), drill the hole for a 1/8 national pipe taper (NPT) tap, and rethread. 1/8 NPT is what my new 100 PSI gauge uses.
Now you doubtless :D ask, why a 100 PSI gauge? Why not a gauge with more resolution, say a 60 PSI gauge if you are going to inflate to 44 PSI?

Because all gauges of this type (bourdon tube) are non-linear in response. You will have noticed that the scale printed on the dial face IS linear, however! Why? The customer will think the gauge is "ugly" if the scale is printed nonlinear, that is, compressed and expanded to make the gauge actually accurate. You will notice a little peg to stop the needle so it cannot go much below "zero", and you can guess why.

Get to the point, blotivating windbag, you scream at your monitor. :D

The gauge IS accurate near the center point of the scale. That is where it is calibrated in production. A 100 PSI gauge is accurate around the 50 PSI mark. Since I inflate to 44, I am close to the accurate area.

All the parts are surplus and hardly cost anything at all.

Any brand/model recommendations for those of us who don't need yet another do-it-yourself project? :)

Lane

I got a hand held digital one, its pretty accurate compared to my analog dial gauges, displays to the tenth of a PSI.. pretty nice and its solid aluminum so it durable as hell.

Was only 15 bucks..

Accutire seems to be the brand on Amazon.com. The reviews are all over the place, so it's next to impossible to make a judgment about which model to get or whether to look for another brand.

Lane

I just ordered one of these: http://www.amazon.com/Accutire-MS-40...3850333&sr=8-1

My mom has had one for a few years and it is still working. I don't know if it is accurate, but it always reads the same for multiple readings in a row, so if it is off it will be easy to correct for.http://ecx.images-amazon.com/images/...fL._SS500_.jpg

Thanks, Jesse! I was leaning toward that one myself, and your note pushed me over the edge. Mine is orderered, too.

Lane

I got one of these for xmas a couple years ago, it lasted EXACTLY one day. No luck getting ahold of the manufacturer either.

The definition of accurate...
 

The definition of accuracy is that you get the same thing several times in a row, the definition of precision is the average of the readings is correct... you either want something both precise and accurate, or at least accurate so you can correct for it...