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Tire gauges

dchoppdchopp Posts: 256
Everyone talks about tire pressure but just how accurate are those gauges you use to measure tire pressure. I started out with a collection of 38 tire gauges (loaned to me)
Various sizes and shapes, some new and some very old. Also we tested some digital
gauges some cheap the others expensive. Our test was conducted at our aircraft maintenance shop and against a highly accurate calibrated air pressure standard. I took each gauge and measured three air pressures consisting of 25, 35 and 45 lbs.
All the testing is done and the results in Parts will be published at various times.
Part one consisted of the most popular tire gauge called the pocket or pen type gauge which cost anywhere from $ 1.00 to $ 2.50 range and they have a white plastic dial reading. I tested 5 new ones (Victor, Monkey Grip etc) that were purchased at nationwide chain and auto stores. Each of the new ones read entirely different pressures with the worst being as much as 6 lbs. lower at 25 lbs. While an exact duplicate gauge read 3lbs. lower at 25 lbs. The new ones where mostly 3 lbs lower at 25lbs but improved at the higher pressures of 35 and 45 lbs. There averages where about 2 lbs. at the higher pressures. I tried exercising the dial a few times by pulling it in and out and taking the readings again and some improved by as much as a lb. at the lower reading. I then test older gauges of this type 3 to 10 years and the results were worse in some cases. It seams the older the gauge the lower the accuracy and they are the worst at the lower pressure. Some were off as much as 8 lbs. By the way all of the gauges we tested read low except one and that had an obvious defect. I took the older gauges and sprayed the dial with WD-40 and exercised it about 10 times and then I went back and redid the test and improved the readings to that of a new gauge. One gauge was 7 lbs lower at 35lbs and after my operation the gauge improved to about 2.5 lbs lower. One gauge that was 10 years old had better accuracy than one that was 3 years old, but generally the older the gauge, the lower the accuracy of gauges of this type. You get what you pay for.
In conclusion. If you want 30 lbs put in the air till your pen type gauge reads 28 lbs. and don't forget to exercise the dial a few times before checking the tire pressure. On the older ones spray the dial with WD-40 or some silicone lube and exercise the dial about 10 times. The average after we got them working was about 2 lbs. low Part 2 deals with more expensive gauges with some surprising results until then-by


  • drew_drew_ Posts: 3,382
    Thanks DCH! Great new topic to start. I have renamed it to "Tire gauges" so that we can discuss anything about tire gauges in this discussion topic, including your posts As mentioned, I look forward to reading the rest of your research!

    Vans, SUVs, and Aftermarket & Accessories message boards
  • tronsr1tronsr1 Posts: 149
    I just received a digital tire guage for a birhtday present {it was purchased at Radio Shack} and I am anxious to get your digital read-out results. I keep 29 lbs. in my 2001 Ford Escape {as per recommended on the door} and find the digital guage very easy to use and also very easy to "read'.
  • dchoppdchopp Posts: 256
    The digital gauges I tested where very accurate over the range, however I found two that where off by as much as 4lbs. at 35 lbs. the owners brought in the directions and it required a self calibration check prior to using. After we did it the accuracy improved to about a 1.5 lbs. So read your directions and see if it requires a self calibration prior to using.
  • tronsr1tronsr1 Posts: 149
    O.K. Will check directions as per above post. Thanks for the input.
  • Does anybody have any good recommendations for brands/models of digital gauges? How about info on price and accuracy?
  • sirfilesirfile Posts: 42
    Accutire makes an excellent digital gauge that is easy to use and has a large readout in .5 pound increments from 5-99 pounds. The gauge is recommended by The Tire Rack, and through for $29.95. I also saw it advertised at Sears today, for only $13.95. It makes a great gift for others [or for yourself]. Be sure to check your tires once a week when the tires are cold.
  • dchoppdchopp Posts: 256
    Tire Gauge Accuracy Part 2. In Part 1, we did an evaluation of the cheaper pocket or pen type gauges. Part 2 consist of the more expensive heavy-duty double-headed type of gauge. Price range is in the $5.50 to $13.00 range. Basically the same names as indicated in Part 1 and a few new ones like ACCU. Most were purchased at local retail and automotive stores such as Napa ,Advance etc. We also tested some Analog or dial type of a gauge. Since these gauges cost more, we expected more from them and they didn't disappoint us. Since these gauges have a much larger range than the cheaper pocket type, we had to expand our testing to the 100lb. range. These gauges were tested at 25,35,45, (lower range) 60, 75, and 90 lb. range, which we called the upper range. Some where brand new, some where old like over 10 years. The gauges with the metal type indicators read about 1 to 2lbs long over the short range and about 1 lb. long on the higher range. Long means that for a known source of air pressure 35lbs. these gauges were indicating 36 or 37 lbs. Exercising the indicators did nothing to improve the accuracy. As these gauges start to get old (6 years and above) they tend to get a little sloppy on the higher end indicating as much as 3 to 5 lbs. higher. The shorter range still remained accurate within 2lbs. The newer type replaces the metal indicator with that of a white plastic dial much like the cheaper pen or pocket type. Easier to read I guess. These type of gauges read differently over the ranges, much like the cheaper ones. On the short range these gauges indicated about 1 to 2lbs. short. So for 35lbs. they would indicate 33 to 34 lbs. On the upper range they were very inconsistent with some reading 1 lb. short while others reading 1 to 2 lbs long, while down in the lower range they were all short. Exercising the indicators a few times improved some in the upper range but not in the lower range. Still overall the accuracy over both ranges was very good. The analog or meter type of gauges were very inconsistent but accurate. Some were short while some were long over the ranges and the brand didn't seam to matter. Two identical read differently. The 8 we tested were within 2 lbs in both the lower and upper ranges. Just remember to check to make sure the gauge reads zero before checking air pressure. Most come with an adjusting screw to do this. I dropped one on the floor and it indicated about 3lbs long. When in the first test, it indicated 1lb short over the ranges. After I zeroed the meter, it was ok. One analog type was reading all over the place as much as 8 lbs off. Here the meter had a static charge on the meter face. I rubbed a little Wd-40 on the meter face and it was ok after that.
    The results show once again you get what you pay for. These types of meters showed pretty good accuracy over the ranges and age didn't seem to slow them down on the lower range.
    Part 3 which consist of Digital Gauges will follow soon. One tested so accurate, I went out and bought one and tested it for repeatability and it indicated the same as the first. Which one was it? Stay tuned Until then---by
  • tronsr1tronsr1 Posts: 149
    Keep up the good work. Your posts are very informative.I am still using my digital guage from Radio Shack and eagerly awaiting the results of your tests.
  • mrdetailermrdetailer Posts: 1,118
    Your research is impressive. Looking forward to your next report.
  • dchoppdchopp Posts: 256
    Tire gauge accuracy Part 3. The final report deals with the accuracy of Digital Gauges. We only had 8 gauges to test in this series, since most people use the gauges we tested in Parts 1and 2. Some of the brands we tested were Victor, Accutire, Majestic, and MG. Since these gauges had indicators up to 100lbs and more we tested them at 25, 35,45,and 50 lbs., which we called the low range. The high range indication consisted of measurements of 60,70, 85 and 100 lbs. All of the digital gauges tested were very accurate over both ranges. We caution you to read your directions carefully, since some of the gages required a self-calibration prior to using. If you don't calibrate them your reading can be off as much as 5 lbs on the lower ranges. The $6.00 gauges we tested were off only 1.5 lbs on the short range and about 2 lbs on the higher range usually 85 lbs. and up. The more expensive Gauges such as Accutire tested the best. The $14.95 gauge tested 0.5 lbs long on the low range and 1lb. long on the higher range. We tested the Accutire lighted background model $30.00 and it read perfectly in the low and higher ranges. It was off by 0.5 lbs (short) at 100 lbs. Every other pressure I tested it at read the correct pressure. I went out and bought one (Sears) and tested it for repeatability and it tested the same. Overall these gauges were very accurate and some do require a self calibration. They were all very easy to read. In time I feel more people will buy them. This concludes my report and I hope it was helpful.
  • tronsr1tronsr1 Posts: 149
    Thanks for the great reports. I have the Accutire $14.95 digital guage and now know I am getting "true readings".
    Thanks Again,
  • mrdetailermrdetailer Posts: 1,118
    Thanks for all of the careful research dchopp.
  • Thanks for analyzing the gauges. I hope you had free access to all the models and did not have to purchase them.
  • lovable90lovable90 Posts: 27
    Thanks, Dchopp for doing all that research. I read your posts yesterday and went out and purchased an Accutire digital gauge today. This model has an indicator up to 150lbs and may require a self-calibration. The original price was $14.95, but Sears had it on sale for $7.99! Such a deal!!
  • mrdetailermrdetailer Posts: 1,118
    adn really enjoyed it. However, I found that all of my low cost gagues are just about as accurate. At least I know I won't have to tote the expensive gauge on vacations.
  • Thanks for the report,dchopp. I bought the Accutire 150lb model today . My old dial gauge is 4.5 lb high (i.e. reads 35 lb when it reads 30.5 on the Accutire)
  • I just bought a new gauge today (dial-type) and noticed a warning about needing safety goggles on the back of the package:


    The increasing number of safety warnings on products continues to amaze me. Has anyone ever even heard of any real accidents involving tire gauges? I used it today, and blatantly risked bodily harm by going without goggles. :)
  • cyranno99cyranno99 Posts: 419
    maybe it is a really cheap gauge and will shot to your face like a rocket when you attach it to the valve of the tire :) They must be really afraid of being sued.
  • dchoppdchopp Posts: 256
    You didn't wear goggles to check your tires with this guage. Shame on you. If you read the fine print it probably tells you to wear protective clothing also.
  • barnonebarnone Posts: 118
    the warning label should include wearing a mouth
    guard and a groin protector just in case the
    gauge would do something funny :)
  • morin2morin2 Posts: 399
    My trusty old Brookstone dial guage just turned 25, given to me by my wife in 1976. Made in USA & used every weekend since new. Just bought 2 new Brookstone tire guages which are now rubber-coated but still made in US, for gifts. Checked the new ones against the 25 year old model on a tire & reading was the same for all 3. Cost is now $10 each.
  • nygregnygreg Posts: 1,936
    I want to thank you for great information in a controlled test. I just happen to have purchased 2 of the Accutire gauges at Sears for $8.99 ea (on sale) about a month ago. After calibrating, they read about 0.5 lbs within each other. Funny thing, my old pen "pop up" type gave me the same reading as the Accutire. Still, I trust the digital more. Again, thanks.

  • pblevinepblevine Posts: 858
    But I didn't see this topic until now. I had gone out and purchased a very rugged analog gauge made by "Meiser". Its solid brass covered in rubber and has a short hose attached for pushing against the tire valve. It seems to be very accurate but I don't have anything to compare it against. It also has another nice feature, a bleeding valve. If your tire is over inflated, keep the gauge's hose attached to the tire a push the bleeding button to lower the pressure in a very controlled manner. Although the gauge is marked in 1 lb increments, I can see differences of about one tenth pound. Has anyone else come across this unit?
  • I just got my first van (Toyota) and am not quite used to dirving one yet. Today while turning in a corner, my right rear wheel rubbed/swiped the curb (gutter).
    I am worried that I might have mis-aligned my wheel. Would anyone know, if I did (aside from getting symptoms on my tire later on or going for an expensive wheel alignment check?
  • If you like "analog" stick gauges, take a look at the made-in-America gauges at your local NAPA store. They are excellent, accurate, and sell for $4-$5. You can't beat them.
  • dudleyrdudleyr Posts: 3,469
    Is the radio shack digital gauge the same as the accutire? They look almost identical.
  • cyranno99cyranno99 Posts: 419
    I bought a pencil type gauge years ago. It was a Camel and came highly rated by CR. I tested against my new digital gauge and they both got the same results. I am happy to say that I did not have to wear special gears while testing... thank you for you time!

    Oh.. I do prefer the digital better even though the pencil is almost as accurate since the digital is within .5 psi. The battery of the digital should last for thousand of uses.... I won't be around to verify that though.
  • Batteries wear out whether used or not. At the end of their lives, they have a downward curve of voltage loss that will adversely affect accuracy. Electric instruments are delicate compared to pneumatic instruments.
    I'll stick with the metal cased old style gauges.
  • What do you expect for a tool that only cost $1, $4, or even $12. An accurate air pressure guage is gonna cost $50-$75. On a daily driven street car or pick-up 2 or 3 pounds isn't going to make any noticable difference in performance. The important thing is that all 4 tires are the same pressure. Buy a cheap $4 stick guage and forget about batteries. If all 4 tires are 2 pounds too high or 1 1/2 pounds too low, the average person will never be able to tell the difference. As long as all 4 tires are the same that's all that's important. I have learned through experence at the race track never barrow your friends guage. I only set up my race car with my guage not to say it is accurate, but a guage that is 1 pound off will always be 1 pound off.
  • I've seen tire gauges that can be off by as much as 3psi. Imagine someone driving with 26psi. Boy! That sure helps the fuel economy of the car, not to mention tire wear.

    As for battery in a digital gauge, the one that I have said "You observe "L" on the display. the power supply has been depleted. Return to factory for free replacement...." anywway, I am sure that they set it to stop measuring when the battery is too low. Observe the same behavior in your cordless phone or whatever....
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