for factory installed (brand,type) of tyre. You change brand,type,rating of tyre throw the hand book out the window. as they are not apple to apples. more apples to oranges.
wil2813
Well-Known Member
stick to that cause if you run someone over & kill them atleast you are following recommended pressures
discool
Well-Known Member
stick to that cause if you run someone over & kill them atleast you are following recommended pressures
But then there's some allowance I would hope as tyre pressure will increase while rolling.
I have collected five pressure gauges over the years, the original Dunlop stick style both read the same and three digital which over or under state state the tyre pressure compared with the stick type, even my local filling station gauge reads different.
Then there's the time the pressure reading is taken, cold tyres the say I've found that the two tyres on the sunny side of the street can read up to 4 psi higher.
So it looks if the ideal time to take tyre pressures is on a dull day or at night plus a certified domestic tyre pressure gauge...if there is such a thing.
I would hope the tyre fitters and filling stations like other industries use certified equipment, there's no need to be accurate but the difference should be stated.
brian47
Well-Known Member
There is a standard or certified pressure against which all other air pressure measuring devices are (or should be) calibrated. That pressure is regarded as 1 atmosphere equates to exactly 1,013,250 dynes per square centimetre.
1 atmosphere can also be stated as 1013.25 millibars and converted to 14.69595 (14.7) pounds per square inch.
As each calibration "sub-standard" steps away from the international standard then a quotable error is introduced often given as + or - a certain percentage at the calibrated pressure. The further away from the standard the device is, the greater the error.
Where a garage or tyre fitting business uses guages; pressure, torque wrenches and so on, then they should be calibrated, that work often being undertaken by a specialist contractor, some of whom use a mobile service.
In the case of purchased tyre pressure guages, the error is often not quoted, but I would hazard a guess at it being as small as +or- 10% up to as much as +or- 20%, depnding upon the quality of the guage.
Regarding temperature, it is recommended that tyre pressures are measured when cold, so yes first thing in the morning before the sun comes up would be best.
　
Last edited:
wil2813
Well-Known Member
thebiglad
Well-Known Member
We're getting very deep into this aren't we?
The number of vehicles I see running round with little or no air in one or more tyres leads me to suggest that if we could achieve every driver checking their tyres at least once a week; that would be a huge increase in road safety.
What concerns me most is that often drivers don't know they are running on nearly flat tyres - what are they thinking???? Not about the 'feel' of their vehicle obviously !
Right, I'm getting down off my high horse and going to the fayre.........................
Dave
The number of vehicles I see running round with little or no air in one or more tyres leads me to suggest that if we could achieve every driver checking their tyres at least once a week; that would be a huge increase in road safety.
What concerns me most is that often drivers don't know they are running on nearly flat tyres - what are they thinking???? Not about the 'feel' of their vehicle obviously !
Right, I'm getting down off my high horse and going to the fayre.........................
Dave
