Where to find an accurate tire pressure gauge???

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
reset.
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).

 

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

 

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.

 

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

Richard.

 

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

Larry
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.
|
|

 

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.

 

Well consider the source of the Condemner Retards quote!

 

Now, now, a tire guage is just the sort of basic, simple consumer item
that they are actually qualified to test!

Ted

 

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.

 

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

 

What a load of bull sh*t.

 

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

 

That is BS also.

Run at max and your tires will wear out faster, although just the center of the
tread.
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.

 

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.

 

A classic sign of under inflation.


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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?

 

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

 

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

 

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')

 

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')