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Farkle Purchasing System
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Discussion Starter #1
I've been using a Cruz Tools TirePro Digital Tire Gauge for the last year or so.

It's great because it's compact, easy to use, and the battery lasts forever.

However, I have no idea how accurate it is, or isn't. Is there any practical way to calibrate a tire gage at home?

This comes up because I've found the pen-type gages to be unreliable. At one point I owned 3 of them. 2 were brand new, 1 was about 8 years old, and all 3 disagreed with each other by as much as 2 PSI.
 

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I bought a Slime digital gauge a couple weeks ago when setting pressures for the Darkside. Is it more accurate than a pencil gauge? I think so? Does a couple pounds +/- really matter for street riding? Not nearly as some would lead you to believe.

What nice is it does produce repeatable results. If I use a pencil gauge and 10 times in a row I'll get at least 7 different numbers. Just like Veglia gauges are good for letting you know you are moving pencil gauges are good at telling you, you have air in your tires
 

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I've never had a problem with my stick gauges. I've got two that have a different displays but they both show the same pressure when I check my tires.
 

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This reminds me of my early 20's when the popular tire was a Pirelli Phantom, a few friends and I got onto the subject and one friend explained that to get the best out of them they needed a extra 10psi front and rear, none of us agreed with him.

On our next ride together we both checked our pressures at the local fuel stop, he commented that their gauge was off by 10psi, I believed their gauge was correct.

We then compared his gauge with 3 more, his gauge was wrong by 10psi compared with all the others.

The thing that amazes me is he had the ability to work out his tires worked best at the correct pressure and that was 10psi above what his gauge was telling him.

My Dad was always in the tire business, they were what put food on our table and a roof over our heads, when I got into road bikes he gave me a Michelin branded gauge in a box and he told me it was the most accurate one on the market and my life could depend on it, I have know idea if he was talking crap but I lived by those words until I lost that gauge in my early 50's.

I now only use TPMS's on my cars and bikes, when mixing systems I get the same results so I guess they are close enough.....
 

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Not too long ago Motorcycle Consumer News tested a bunch of tire gauges and found that the midpriced pencil gauges were about as reliable, accurate and repeatable as anything else. They found a couple of cheap digital gauges that were good too. (Just because the digital will read out to hundredths of a pound doesn't make them accurate.)

I occasionally go down to the local shop where I buy my tires. I ask them to check my pressure and then immediately check it against my gauge.

...................shu
 

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Serious question......how do you know a gauge is accurate? What do you check it against? I would bet a beer that most tire shops have not had their gauges calibrated in the last year, if not longer and have you noticed how they are handled? So....how do we know whether our gauges are accurate or not. Personally I have all types of gauges and find them all within reason. ie. the bikes feel right. The worst thing about a digital gauge is that the battery seems to be dead just when you need it. Best thing about a dial gauge....easiest to read without my reading glasses. Best thing about a pencil gauge....takes up least room in my tank bag.
 

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If you have a group of gauges and they all tend to read the same value you can probably figure that by consensus they might be accurate. Good question, "When was your gauge last calibrated?" Probably never.
 

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I have a handful of gauges of all varieties. About once per year, I test them all on the same tire and if any are way out of bounds (as compared to the others) I throw it away. I don't know where I could go to get my gauges calibrated, so I figure this is the next best thing.
 

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What difference is one to two psi tire pressure going to make, to influence your riding experience? The tire guage gives the rider a general idea of the current tire pressure. Each rider has his personal tire pressure preference, based on the type of ride being done and tire choice. Take a reading, pump air in a cold tire if required, then ride and test for tire warmth, after riding a reasonable distance. If the tire is hot (to hand touch) after the ride, most likely the tire pressure is too low. A warm tire after a ride is good, while a hot tire, is not. Measuring a warm / hot tire air pressure will give a false read to a reading of a cold tire.
 

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Farkle Purchasing System
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Discussion Starter #13
What difference is one to two psi tire pressure going to make, to influence your riding experience? The tire guage gives the rider a general idea of the current tire pressure. Each rider has his personal tire pressure preference, based on the type of ride being done and tire choice. Take a reading, pump air in a cold tire if required, then ride and test for tire warmth, after riding a reasonable distance. If the tire is hot (to hand touch) after the ride, most likely the tire pressure is too low. A warm tire after a ride is good, while a hot tire, is not. Measuring a warm / hot tire air pressure will give a false read to a reading of a cold tire.
Tire wear. It does matter, especially over several thousand miles.
 

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Farkle Purchasing System
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Discussion Starter #15
I have a handful of gauges of all varieties. About once per year, I test them all on the same tire and if any are way out of bounds (as compared to the others) I throw it away. I don't know where I could go to get my gauges calibrated, so I figure this is the next best thing.
There is a certified instrument testing & calibration business in the next town over from here. However, for what they would have to charge it makes more sense just to buy another tire gauge.

The Cruz Tools digital gage is pretty cheap now. Might pick up a second one just for giggles & comparison.
 

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I have a calibrated pressure gauge at work that is calibrated once a year. I built a rig to test tire pressure gauges with it. It is very rare to find a gauge that is accurate. Most are 2-3 psi either high or low. This includes everything from expensive Motion Pro gauges to $5 electronic ones from the counter of the local auto parts store. Most of my friends have had me check their gauges and I mark them with a correction factor. I was on a ride one time when one of the riders was complaining about how stiff and bumpy his ride was. I checked his tire pressure and it was 20 psi high. When asked about what pressure gauge he used, he responded that it was a Motion Pro. He brought it by my shop a few weeks later and sure enough, it was reading 20 psi high.
If a few psi makes a difference to you, get your gauge cal'd.
 

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Weather is another factor, by running TPMS I can see the rise and fall of my pressures.
As a general rule if I set my pressures to the recommended PSI and under normal ridding I gain 2 psi in winter & 3 in summer.
If I push hard I gain 4 & if I go full on boy racer I gain 5, that is all just a average many things like wet weather or road surface changes things again.
I don't care how long my tires last so long as they stick, I test all my tires for stopping distance and I'm unable to tell the difference with a couple of PSI.
 

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Farkle Purchasing System
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Discussion Starter #19
I got a second Cruz digital tire gage.

It agrees with my old one, to the 0.1 psi. I'm not sure I really believe that decimal place, but it'll do.
 

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My most used guage, and one that I always carry is one that was supplied as part of the original tool kit on my former Kawasaki Z1000 A1. It is now over 40 years old and still works perfectly. I have two other tyre guages, one of which is an expensive digital. All are within 1/1.5 psi of each other. Which is the most accurate ? No idea.
 
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