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Re: Tire Gauge?
Sparky wrote: > do_not_spam_me@my-deja.com wrote: > > Dial guages can be as accurate as pencil guages, but > > when Consumer Reports last tested guages, in 2/1993, > > all of the least-accurate guages (off by +- 4 PSI > > average) were of the dial type, > > That's a long time ago, dude. True, but the results were so consistent that I doubt they've changed much over the years. Their previous evaluation was published around 2/1987. > > and no pencil-type guage erred more than +- 2 PSI. The > > most accurate pencil-type guages have shims at the end > > of their coil spring for calibration. > > But don't the stick type guages lend themselves more easily to being > misread (which can make the reading way off)? They are harder to read than dial and digital guages, but I don't see how they could be misread by more than 1 PSI, and that's only when the markings are in 2 PSI increments. |
Re: Tire Gauge?
do_not_spam_me@my-deja.com wrote: > Sparky wrote: > >>do_not_spam_me@my-deja.com wrote: > > >>>Dial guages can be as accurate as pencil guages, but >>>when Consumer Reports last tested guages, in 2/1993, >>>all of the least-accurate guages (off by +- 4 PSI >>>average) were of the dial type, >> >>That's a long time ago, dude. > > > True, but the results were so consistent that I doubt they've changed > much over the years. Their previous evaluation was published around > 2/1987. > > >>>and no pencil-type guage erred more than +- 2 PSI. The >>>most accurate pencil-type guages have shims at the end >>>of their coil spring for calibration. >> >>But don't the stick type guages lend themselves more easily to being >>misread (which can make the reading way off)? > > > They are harder to read than dial and digital guages, but I don't see > how they could be misread by more than 1 PSI, and that's only when the > markings are in 2 PSI increments. However - my experience is that they don't always shoot to the same point every time - even the good ones. |
Re: Tire Gauge?
do_not_spam_me@my-deja.com wrote: > Sparky wrote: > >>do_not_spam_me@my-deja.com wrote: > > >>>Dial guages can be as accurate as pencil guages, but >>>when Consumer Reports last tested guages, in 2/1993, >>>all of the least-accurate guages (off by +- 4 PSI >>>average) were of the dial type, >> >>That's a long time ago, dude. > > > True, but the results were so consistent that I doubt they've changed > much over the years. Their previous evaluation was published around > 2/1987. > > >>>and no pencil-type guage erred more than +- 2 PSI. The >>>most accurate pencil-type guages have shims at the end >>>of their coil spring for calibration. >> >>But don't the stick type guages lend themselves more easily to being >>misread (which can make the reading way off)? > > > They are harder to read than dial and digital guages, but I don't see > how they could be misread by more than 1 PSI, and that's only when the > markings are in 2 PSI increments. However - my experience is that they don't always shoot to the same point every time - even the good ones. |
Re: Tire Gauge?
"Daniel J. Stern" <dastern@127.0.0.1> wrote in message news:Pine.GSO.4.58.0501231114310.2512@alumni.engin .umich.edu... > On Sun, 23 Jan 2005, HLS wrote: > > It is quite accurate as stated. Good gauges are better than bad gauges, > period. There's no manufactured product that MBAs can't entice the Chinese > to make a little cheaper and a little shittier. The statement I quibble with is that a stick type gauge can inherently be as reproducible and accurate as a Bourdon type, assuming equal quality of manufacturing. They aren't, for the reasons I mentioned. The friction component is too variable in the common stick designs. Admittedly, quality construction can improve the performance. These little Bourdon type gauges used on cheap cigarette lighter compressors are all but worthless. 'Dead weight' gauges can be very accurate and have been used to calibrate Bourdon types, BUT a stick gauge is not a dead weight gauge even though there are some similarities. Electronic gauges can give impressive readouts, but the pressure sensing device itself can be a weak point. They sometimes wander in accuracy. But then, who wants to know the exact pressure to 0.1 psi?? It is uselessy finicky to worry about this in passenger applications. If the tires are within a couple of pounds of each other, it is better than good enough for most people. If you are on the pole for Ferrari F1, you have a reason for a bit more careful measurements. |
Re: Tire Gauge?
"Daniel J. Stern" <dastern@127.0.0.1> wrote in message news:Pine.GSO.4.58.0501231114310.2512@alumni.engin .umich.edu... > On Sun, 23 Jan 2005, HLS wrote: > > It is quite accurate as stated. Good gauges are better than bad gauges, > period. There's no manufactured product that MBAs can't entice the Chinese > to make a little cheaper and a little shittier. The statement I quibble with is that a stick type gauge can inherently be as reproducible and accurate as a Bourdon type, assuming equal quality of manufacturing. They aren't, for the reasons I mentioned. The friction component is too variable in the common stick designs. Admittedly, quality construction can improve the performance. These little Bourdon type gauges used on cheap cigarette lighter compressors are all but worthless. 'Dead weight' gauges can be very accurate and have been used to calibrate Bourdon types, BUT a stick gauge is not a dead weight gauge even though there are some similarities. Electronic gauges can give impressive readouts, but the pressure sensing device itself can be a weak point. They sometimes wander in accuracy. But then, who wants to know the exact pressure to 0.1 psi?? It is uselessy finicky to worry about this in passenger applications. If the tires are within a couple of pounds of each other, it is better than good enough for most people. If you are on the pole for Ferrari F1, you have a reason for a bit more careful measurements. |
Re: Tire Gauge?
> > Where does one find a "quality" one then? Many of the dial-type
> > or digital readout gauges tend to be more accurate than the easy > > to find pen-type gauges. I've got a nice dial type made by AccuGage that I bought for about $15 or so from Sporty's Tool Shop (www.sportys.com) Its attachment goes straight in line with the valve stem, so no valve extensions are neccesary. It is encased in hard rubber. 0-60 lbs range. Nice.... :) |
Re: Tire Gauge?
> > Where does one find a "quality" one then? Many of the dial-type
> > or digital readout gauges tend to be more accurate than the easy > > to find pen-type gauges. I've got a nice dial type made by AccuGage that I bought for about $15 or so from Sporty's Tool Shop (www.sportys.com) Its attachment goes straight in line with the valve stem, so no valve extensions are neccesary. It is encased in hard rubber. 0-60 lbs range. Nice.... :) |
Re: Tire Gauge?
On Mon, 24 Jan 2005, HLS wrote:
> > Good gauges are better than bad gauges, period. There's no > > manufactured product that MBAs can't entice the Chinese to make a > > little cheaper and a little shittier. > The statement I quibble with is that a stick type gauge can inherently > be as reproducible and accurate as a Bourdon type, assuming equal > quality of manufacturing. Quibble all you like. Reality has a nasty habit of shooting ugly holes in beautiful theories. |
Re: Tire Gauge?
On Mon, 24 Jan 2005, HLS wrote:
> > Good gauges are better than bad gauges, period. There's no > > manufactured product that MBAs can't entice the Chinese to make a > > little cheaper and a little shittier. > The statement I quibble with is that a stick type gauge can inherently > be as reproducible and accurate as a Bourdon type, assuming equal > quality of manufacturing. Quibble all you like. Reality has a nasty habit of shooting ugly holes in beautiful theories. |
Re: Tire Gauge?
"Daniel J. Stern" <dastern@127.0.0.1> wrote in message news:Pine.GSO.4.58.0501241304220.7341@alumni.engin .umich.edu... .. > > Quibble all you like. Reality has a nasty habit of shooting ugly holes in > beautiful theories. It isnt a theory, Light Bulb Boy. Just the truth. |
Re: Tire Gauge?
"Daniel J. Stern" <dastern@127.0.0.1> wrote in message news:Pine.GSO.4.58.0501241304220.7341@alumni.engin .umich.edu... .. > > Quibble all you like. Reality has a nasty habit of shooting ugly holes in > beautiful theories. It isnt a theory, Light Bulb Boy. Just the truth. |
Re: Tire Gauge?
>y_p_w wrote >However - my experience is that they (stick gauges) don't always >shoot to the same point every time - even the good ones. That's always been my complaint. I am addicted to dial gauges. Many years ago I took my collection of assorted tire gauges with me on a trip to Akron and tested their accuracy at one of the tire research & testing facilities where I had once worked. The dial gauges were consistently more accurate and more precise. I identified the gauge which was the best and I have carefully protected it for years as my reference gauge for calibrating others. I kept the dial gauges and labeled them on the back (eg: Reads + 1/2 psi). I gave away all of the stick gauges. A note or two on evaluating gauges. Suppose that you have two gauges and you test each one of them 10 times in an attempt to measure a particular psi: 1) Take the average reading for gauge A over 10 tests and the average reading for gauge B over 10 tests. If the average psi reading for gauge A is closer to the actual psi, then gauge A is more "accurate" than gauge B. Accuracy is a measure of how probable the gauge is to give a correct reading. 2) Now, for gauge A look at the deviation from the true psi for each of the 10 readings. Just use the absolute value of the deviation, ignoring plus or minus. Thus a reading that is off by -0.75 psi would have an absolute deviation of 0.75. Sum these 10 deviations. Do the same for gauge B. If the sum of deviations for gauge A is less than for gauge B, then gauge A is said to be more "precise" than gauge B. Precision is a measure of how consistent a gauge is with its readings. Precision is the important criteria for selecting a tire gauge. It is the true measure of how well the gauge was manufactured. A gauge which is very precise but not particularly accurate can be recalibrate to be both precise and accurate. The opposite is not true. A gauge which is precise can be recalibrated the lazy way that I use - just put a piece of tape on the back indicating how high or low it tends to read. Or you can do it properly by opening the gauge and recalibrating physically. Analogies: 1) Consider ruler A which is extremely well machined and has laser etched gradients down to 1/1000" of an inch. But the ruler scale runs from 1" to 13" rather than the standard 0" to 12". Also, consider ruler B which is one of those cheap 25 cent plastic rulers used by students. Measurements taken with ruler A will always but much less accurate than those taken with the cheap ruler B. But it is obvious that ruler A is a much more precise device which you can easily "recalibrate" to give superior measurements compared to ruler B. 2) Consider 2 pistols which are new-in-the-box. The more poorly manufactured pistol may be more accurate when you first use it. But the better built one will probably be more precise and after a bit of sighting-in at the range, you will have it adjusted to be the more accurate of the two. It may have started off producing nice tight patterns off to the edge of the target. This is no concern to the experience shooter who knows that he can adjust the sights to move that pattern over top the bullseye. |
Re: Tire Gauge?
>y_p_w wrote >However - my experience is that they (stick gauges) don't always >shoot to the same point every time - even the good ones. That's always been my complaint. I am addicted to dial gauges. Many years ago I took my collection of assorted tire gauges with me on a trip to Akron and tested their accuracy at one of the tire research & testing facilities where I had once worked. The dial gauges were consistently more accurate and more precise. I identified the gauge which was the best and I have carefully protected it for years as my reference gauge for calibrating others. I kept the dial gauges and labeled them on the back (eg: Reads + 1/2 psi). I gave away all of the stick gauges. A note or two on evaluating gauges. Suppose that you have two gauges and you test each one of them 10 times in an attempt to measure a particular psi: 1) Take the average reading for gauge A over 10 tests and the average reading for gauge B over 10 tests. If the average psi reading for gauge A is closer to the actual psi, then gauge A is more "accurate" than gauge B. Accuracy is a measure of how probable the gauge is to give a correct reading. 2) Now, for gauge A look at the deviation from the true psi for each of the 10 readings. Just use the absolute value of the deviation, ignoring plus or minus. Thus a reading that is off by -0.75 psi would have an absolute deviation of 0.75. Sum these 10 deviations. Do the same for gauge B. If the sum of deviations for gauge A is less than for gauge B, then gauge A is said to be more "precise" than gauge B. Precision is a measure of how consistent a gauge is with its readings. Precision is the important criteria for selecting a tire gauge. It is the true measure of how well the gauge was manufactured. A gauge which is very precise but not particularly accurate can be recalibrate to be both precise and accurate. The opposite is not true. A gauge which is precise can be recalibrated the lazy way that I use - just put a piece of tape on the back indicating how high or low it tends to read. Or you can do it properly by opening the gauge and recalibrating physically. Analogies: 1) Consider ruler A which is extremely well machined and has laser etched gradients down to 1/1000" of an inch. But the ruler scale runs from 1" to 13" rather than the standard 0" to 12". Also, consider ruler B which is one of those cheap 25 cent plastic rulers used by students. Measurements taken with ruler A will always but much less accurate than those taken with the cheap ruler B. But it is obvious that ruler A is a much more precise device which you can easily "recalibrate" to give superior measurements compared to ruler B. 2) Consider 2 pistols which are new-in-the-box. The more poorly manufactured pistol may be more accurate when you first use it. But the better built one will probably be more precise and after a bit of sighting-in at the range, you will have it adjusted to be the more accurate of the two. It may have started off producing nice tight patterns off to the edge of the target. This is no concern to the experience shooter who knows that he can adjust the sights to move that pattern over top the bullseye. |
Re: Tire Gauge?
>Daniel J. Stern wrote >Quibble all you like. Reality has a nasty habit of shooting >ugly holes in beautiful theories. Reality does shoot holes in theory sometimes, but fortunately that is the exception rather than the rule. What sort of gauge is being used by the folks who demand accuracy? You local tire retail outlet, gas station or auto service center don't count - being accurate within a few PSI is generally considered adequate for them. I'd look to the following: - The tire R&D field, which I've said only uses dial gauges by my observations. There are many tires tests which are very sensitive to proper inflation - braking, resonant frequency, tire uniformity, traction, endurance ("run to failure" testing), etc. The testers use dial gauges. - Commercial & military aircraft. I don't know about this one. - Serious auto racers. The few that I know wouldn't touch a stick gauge, and this includes one acquaintence who is very fussy about tire pressures for his Shelby Cobra and and his Indy car. - HVAC manifold/gauge sets. I've never seen a pop-up style gauge on an AC manifold set. I've got 3 sets and they've all got dial gauges. To me, the high pressure gauge is mostly a "sanity check" and I could live with rough appoximations there, but I want accuracy to less than 1 psi on the low side readings. - Oxy-Acetylene manifold/gauge sets. Mine has dial gauges and so do all the sets that I've ever seen. Gideon |
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