The tyre's were set at a tyre dealer at 35lb
Then I tried a digital gauge from Argos which is incorporated in a 12V pump 
from Argos.
..The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a 
difference of 3.5lb. Not alot of difference, but I had to change 2 worn 
tyres
due to low tyre pressure which I thought was set at 33lb originally so I 
want to set them as accurate as I can.
The tyre's were all checked when cool.
Anyone have any idea where to buy an accurate gauge and what manufacturer.

"Merlin"  wrote in message 
news:dg9vjm$rho$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

> The tyre's were set at a tyre dealer at 35lb
> Then I tried a digital gauge from Argos which is incorporated in a 12V 
> pump from Argos.
> .The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a 
> difference of 3.5lb. Not alot of difference, but I had to change 2 worn 
> tyres
> due to low tyre pressure which I thought was set at 33lb originally so I 
> want to set them as accurate as I can.
> The tyre's were all checked when cool.
> Anyone have any idea where to buy an accurate gauge and what manufacturer.



How do you define accurate????  An 'accurate' gauge is one that reads within 
a set tolerance of the actual value.  Any of the above are most likely 
accurate to a degree and if the set tolerance is, for arguments sake,  2 
PSI of the true value then all of the above would probably be defined as 
within the required level of accuracy.  An accurate gauge this week might 
not be accurate next week after it has been used, abused etc and would 
therefore need to be verified against a standard to ensure it was still 
within defined tolerance levels.  These levels would most likely be  1 or 2 
PSI anyway.  I really wouldn't worry about but if you must then take the 
average of 3 readings oobtained from 3 separate sources!

Andy

Merlin wrote:


> The tyre's were set at a tyre dealer at 35lb
> Then I tried a digital gauge from Argos which is incorporated in a 12V
> pump from Argos.
> .The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a
> difference of 3.5lb. Not alot of difference, but I had to change 2 worn
> tyres
> due to low tyre pressure which I thought was set at 33lb originally so I
> want to set them as accurate as I can.
> The tyre's were all checked when cool.
> Anyone have any idea where to buy an accurate gauge and what manufacturer.


A while ago I had access to a piece of test equipment at work that could
very accurately measure and create pressure. It had a calibration
certificate. Purely out of interest, I made a rig to test pressure gauges.

I already had an expensive bourdon tube gauge. I bought a really cheap
digital one from Halfords. I borrowed a few other gauges from colleagues
and tested them in 1 psi steps from 10 to 30 psi. I repeated the test on
each gauge three times. (I'm glad my employer doesn't read Usenet!)

Briefly, some of them, including my posh one, were misreading by more than
10%. The most accurate one was the one from Halfords that was less than a
fiver! It was within 2% throughout the tested range.

Clearly, the next one on the shelf of the same type might be way out. My
conclusion was that it is not possible to know how accurate a gauge was
without being able to test it. I'm sorry, I'm sure that was not what you
wanted to hear.

As an aside, if I back my car out of the garage on a sunny day, spend ten
minutes checking fluids and cleaning the windscreen and then check the tyre
pressures the tyres on the "sunny" side of the car will be 2 or 3 psi
higher than the side in the shade. It really can't be an exact science it
seems. 

Chris

-- 
Remove prejudice to reply

Only as accurate as the last calibration


"Merlin"  wrote in message
news:dg9vjm$rho$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

> The tyre's were set at a tyre dealer at 35lb
> Then I tried a digital gauge from Argos which is incorporated in a 12V
pump
> from Argos.
> .The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a
> difference of 3.5lb. Not alot of difference, but I had to change 2 worn
> tyres
> due to low tyre pressure which I thought was set at 33lb originally so I
> want to set them as accurate as I can.
> The tyre's were all checked when cool.
> Anyone have any idea where to buy an accurate gauge and what manufacturer.
>
>

"Merlin"  wrote in message
news:dg9vjm$rho$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

> The tyre's were set at a tyre dealer at 35lb
> Then I tried a digital gauge from Argos which is incorporated in a 12V
pump
> from Argos.
> .The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a
> difference of 3.5lb. Not alot of difference, but I had to change 2 worn
> tyres
> due to low tyre pressure which I thought was set at 33lb originally so I
> want to set them as accurate as I can.
> The tyre's were all checked when cool.
> Anyone have any idea where to buy an accurate gauge and what manufacturer.


It doesn't really matter. Digital guages IME are reasonably accurate. Just
use the same guage and pressure the tyres by trial and error, starting at
the manufacturers recommended pressure, and initially keep an eye on the
wear pattern. 1-2 psi either way is not likely to make much difference, but
if the tyre shows an uneven wear pattern, adjust the air pressure to correct
it. More wear across the middle, reduce the pressure. More wear on the
outside of the tread increase the pressure. Adjust it by 1 or 2 pounds until
the wear pattern is even across the tread. As long as you use the same
guage, it wont matter what the actual reading is.
Mike.

"Merlin"  wrote in message
news:dg9vjm$rho$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

> The tyre's were set at a tyre dealer at 35lb
> Then I tried a digital gauge from Argos which is incorporated in a 12V
pump
> from Argos.
> .The Argos pump reads 33lbs, a friends digital meter read 36.5lb, a
> difference of 3.5lb. Not alot of difference, but I had to change 2 worn
> tyres
> due to low tyre pressure which I thought was set at 33lb originally so I
> want to set them as accurate as I can.
> The tyre's were all checked when cool.
> Anyone have any idea where to buy an accurate gauge and what manufacturer.
>

The important thing is the pressure differential in each tyre as opposed to
the actual value of that pressure (within reason obviously). Don't worry too
much about it - I always use a couple of psi more pressure than recommended
anyway.