Where to find an accurate tire pressure gauge???

Discussion in 'General Motoring' started by TomKan, Aug 1, 2005.

  1. TomKan

    TomKan Guest

    Where can I purchase an ACCURATE tire pressure gauge? Pencil type,
    digital, air hose attached, I don't care.
    I purchased a digital one that was supposed to be accurate but you
    couldn't reset it back 0 psi, you had to wait for the gauge to do this
    on its own. This took over a minute for the reset. Then you add a
    little air, and check it. again and now you're back to another minute
    Car Talk mentioned that there are digitals that are accurate within one
    tenth a pound psi and can be purchased for less than $20. Of course
    they gave no brand or retailer.
    I don't want to spend an arm and a leg. Oh, one more requirement, it
    has to have the capacity of measuring air pressure up to 80 psi
    (bicycle tires).
    TomKan, Aug 1, 2005
  2. I feel compelled to explain something about accuracy on guages here.

    Suppose I have a guage that has a scale from 0psi to 50psi that is
    4% innacurate.

    Suppose you have a guage with a scale that goes from 0psi to
    120psi that is 2% innacurate.

    We both measure our car tires at 35psi. Which one of us has
    a more accurate reading?

    Answer: _I_ do. The reason: With my guage the max deviation
    it will have is + or - 2psi

    With your guage the deviation it will have is + or - 2.5psi. At
    35psi, your actual pressure could be anywhere from 32.5psi
    to 37.5psi. By contrast, with me at 35 psi my actual pressure
    could be anywhere from 33psi to 37psi

    This should tell you that trying to get a one-size-fits-all tire
    guage isn't the way to get high accuracy.

    But wait, there's more!

    Suppose I have a tire guage that is 100% accurate.

    Lets say I used this accurate tire guage to measure my tires on
    a cold day after I had been driving for a while. Ambient air temp
    is about 50 degrees and tire air temp is about 80 degrees.

    A week later the weather has changed and it's now sunny and hot.
    Air temp is about 80 degrees and after a while of driving on the
    road, tire temp has gone up to 130 degrees.

    Guess what - that hot weather has just pushed the tire PSI up by
    5 psi.

    Ted Mittelstaedt, Aug 2, 2005
  3. TomKan

    TomKan Guest

    OK, perhaps I should "wephase my question." Where can I buy two
    accurate gauges, one for lower passenger car tire pressures, and one
    for higher bicycle tire pressures?

    Every door jamb tells you the cold tire and hot tire pressures.
    TomKan, Aug 2, 2005
  4. TomKan

    Richard Guest

    Consumer Reports found that most of the digital readout guages were
    accurate. That has been my experience.

    Richard, Aug 2, 2005
  5. TomKan

    Larry Crites Guest

    Oh boy. Here we go with the Consumer Reports garbage, again.

    Behold Beware Believe

    "Richard" <rfeirste at nycap.rr.com> wrote in message
    | Consumer Reports found that most of the digital readout guages were
    | accurate. That has been my experience.
    | Richard.
    Larry Crites, Aug 2, 2005
  6. TomKan

    Art Guest

    The one I bought at Radio Shack has a unreplacable battery but seems very
    accurate and consistant and resets in a few seconds. You throw it away when
    the battery goes bad. It uses a lithium battery. I have lithium batteries
    on a shelf for over 10 years and they are still good so I am not too worried
    about the battery aging and i cannot imagine it uses much juice. I've had
    the gauage about 6 years now.
    Art, Aug 2, 2005
  7. Well consider the source of the Condemner Retards quote!
    Daniel J. Stern, Aug 2, 2005
  8. Now, now, a tire guage is just the sort of basic, simple consumer item
    that they are actually qualified to test!

    Ted Mittelstaedt, Aug 3, 2005
  9. TomKan

    Richard Guest

    Yes, but this newsgroup is blessed with thought police who want to put a
    halt to any discussion that includes objective reports concerning a Consumer
    Reports test result.

    Richard, Aug 3, 2005
  10. If you take the tire pressure for your tires off the door jamb you
    are cutting their life down.

    The best pressure is to fill the tires up to about 5psi under the
    max pressure stamped in the tire sidewall, then take them out
    for a good run, get them up to operating temp, then stop and
    bleed any extra air off to get the psi right at max pressure.

    You will get the best gas mileage, the best handling, and the
    longest tire life this way. You will NOT get the most plush
    ride. But, automakers have been saving money on car suspensions
    for ages by lowering the tire pressure instead of more expensive
    shocks and a better suspension.

    Ted Mittelstaedt, Aug 3, 2005
  11. TomKan

    High Sierra Guest

    What a load of bull sh*t.
    High Sierra, Aug 3, 2005
  12. TomKan

    Matt Whiting Guest

    Yes, the max pressure on the tire is a cold inflation pressure and the
    temperature rise during use has already been accounted for. I tend to
    run at or near max pressure also. You get a slightly rougher ride,
    although with radials it isn't that noticeable and I get better tire
    life and fuel economy.

    Now you can rail about the ills of running a pressure higher than the
    manufacturers specify.... :)

    Matt Whiting, Aug 3, 2005
  13. TomKan

    High Sierra Guest

    That is BS also.

    Run at max and your tires will wear out faster, although just the center of the
    Ride will be considerably rougher and mileage increase will be minimal.

    If you want a good increase in mileage, slow down a couple of miles per hour.
    High Sierra, Aug 4, 2005
  14. TomKan

    Art Guest

    It used to be that the edges used to wear first in the fronts so adding a
    few extra pounds made sense. These days, at least with the Chryslers I've
    owned, the front and rears wear incredibly evenly. On my 94 LHS I never had
    the car aligned once. On my 99 300M the car was aligned once when the front
    struts had to be replaced because a giant pothole snuck up on me.
    Art, Aug 4, 2005
  15. TomKan

    High Sierra Guest

    A classic sign of under inflation.

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    High Sierra, Aug 4, 2005
  16. TomKan

    SDG Guest

    NO! Don't do this Ted (or anyone else.)

    This pressure has been determined by the manufacturer based on many factors
    (least of which is tire life, and most of which is your safety.) A car is
    dynamic and can change weight and load ratios very quickly. Not to mention
    the dynamic loads imposed on it from the normal stress of acceleration,
    braking and road hazards. Tire pressure is not a constant, it rises due to
    heat and shoots through the roof when you hit a pothole. There are many,
    many factors taken into consideration by a manufacturer concerning the final
    recommended air pressure.

    A tire is an extremely complex and dynamic part and the inflation pressures
    chosen represent the best compromise under the best and worst conditions
    (when you will need the all of the stability you can get.) Operate the tire
    in an over-inflation mode and lose a great deal of friction and stability.
    (And in-truth, you will SHORTEN the tire life, not prolong it. This
    of-course is even more pronounced for under-inflated tires.)

    Operate the vehicle exactly like the manufacturer intended it to be, follow
    the instructions of the engineers, NOT the advice of the parts counter.

    To recommend that tire be over-inflated is simply very bad advice and shows
    ignorance all that's involved.

    Who knows more; the combined talent of the engineering department of a major
    automotive manufacturer or the mechanic who decides he know better?
    SDG, Aug 4, 2005
  17. TomKan

    Matt Whiting Guest

    Nope, actually my tires wear much more evenly when inflated to the max
    PSI. I've done this for 20+ years now and never had tires wear out
    first in the center. I ran a set of Michelins on a Jeep Comanche for
    90,000 miles ... and this was on a 4x4! The tires were rotated every
    10,000 miles and wore out very evenly. Friends and family members who
    run the lower pressures recommended by the car makers never match my
    tire life.

    Sorry, but that isn't my experience. Both of my Chrysler minivans like
    35 PSI just fine and my K1500 likes 50 PSI just fine, except I do lower
    the rears to 40 PSI when the truck is empty.

    I drive 55 already and can't stand to go any slower. And higher tire
    pressure will give better fuel mileage at even a slower speed. :)

    Matt Whiting, Aug 4, 2005
  18. TomKan

    Matt Whiting Guest

    Yes, the pressure given by the vehicle manufacturer is a COMPROMISE that
    tries to be all things to all people and all conditions, but isn't
    optimal for any one condition. Since I know how I drive, I adjust the
    pressure to optimise the parameters of interest to me, which are tire
    life and fuel economy. I'm willing to sacrifice ride quality to achieve
    that and ride quality is the primary reason for the lower pressures the
    car makers recommend. As long as you don't exceed the max pressure
    listed on the sidewall by the tire maker, you aren't compromising safety
    or shortening tire life - you likely increase life as you run at lower
    tire temps at the higher pressure. Modern belted radials do not wear
    out in the center at the max pressure listed on the sidewall, at least
    not in the vehicles I've owned in the last 20 years (all on the heavy
    side though, such as minvans and full-size pickups). Maybe this isn't
    true for a Neon or Echo, but I have no experience with such light cars.

    Matt Whiting, Aug 4, 2005
  19. TomKan

    Bill Putney Guest

    Which goes along with what Art was saying. There was a time in the
    earlier days of radial tires that the recommended air pressures were a
    lot lower than they are today (typically 24 to 26 psi IIRC). I
    distinctly remember a point in time when the recommendations suddenly
    were for higher pressures (28 to 30 psi) - probably about the time that
    wear patterns became more even acorss the tread. Art is correct that
    radial tires on the front used to wear out on the edges, and I have no
    doubt that that was in the days of the lower pressure recommendations.

    Also, trends have been to wider treads which, for a given air pressure
    tends to lower the pressure requirements, i.e., tends to move the wear
    away from the edges and more towards the center.

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    adddress with the letter 'x')
    Bill Putney, Aug 5, 2005
  20. TomKan

    Bill Putney Guest

    SDG wrote:

    Oh man! That would very much depend on the particular engineering
    department and the particular mechanic - I wouldn't paint either "group"
    with a super broad brush. We've all seen some pretty blatant examples
    of crappy engineering that passed thru the review of the "high
    performance work team" of engineers. As well as very good
    engineereing...as well as mechanics who understand very well where the
    engineers went wrong...as well as mechanics who don't have much
    understanding at all of what a good design is or isn't.

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    adddress with the letter 'x')
    Bill Putney, Aug 5, 2005
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